<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:0a59d077-9fd2-4b8c-abec-a970417c858f,g:35dc5018-fe41-432c-b800-3c588fd30db0-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://ouster.com/role/CoverPage" xlink:type="simple" xlink:href="oust-20241231.xsd#CoverPage"/>
  <link:definitionLink xlink:role="http://ouster.com/role/CoverPage" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_d21f921d-9cad-426e-94a8-d4bda7eae271" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentInformationTable_d21f921d-9cad-426e-94a8-d4bda7eae271" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9d35007e-5a50-4462-92b1-a7ba3a5e4208" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_d21f921d-9cad-426e-94a8-d4bda7eae271" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9d35007e-5a50-4462-92b1-a7ba3a5e4208" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_9d35007e-5a50-4462-92b1-a7ba3a5e4208_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9d35007e-5a50-4462-92b1-a7ba3a5e4208" xlink:to="loc_us-gaap_ClassOfStockDomain_9d35007e-5a50-4462-92b1-a7ba3a5e4208_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0fbd1027-6b1b-43dc-b264-3b920a9ec598" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9d35007e-5a50-4462-92b1-a7ba3a5e4208" xlink:to="loc_us-gaap_ClassOfStockDomain_0fbd1027-6b1b-43dc-b264-3b920a9ec598" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_985d4770-2b24-46ef-ac9a-f6f7c399eddb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0fbd1027-6b1b-43dc-b264-3b920a9ec598" xlink:to="loc_us-gaap_CommonStockMember_985d4770-2b24-46ef-ac9a-f6f7c399eddb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_WarrantsToPurchaseCommonStockExpiring2026Member_a4aeac49-aea7-4b61-a072-cac4fa086a93" xlink:href="oust-20241231.xsd#oust_WarrantsToPurchaseCommonStockExpiring2026Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0fbd1027-6b1b-43dc-b264-3b920a9ec598" xlink:to="loc_oust_WarrantsToPurchaseCommonStockExpiring2026Member_a4aeac49-aea7-4b61-a072-cac4fa086a93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_WarrantsToPurchaseCommonStockExpiring2025Member_e3429e1c-c148-45d3-9777-75fcd4e9f49a" xlink:href="oust-20241231.xsd#oust_WarrantsToPurchaseCommonStockExpiring2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_0fbd1027-6b1b-43dc-b264-3b920a9ec598" xlink:to="loc_oust_WarrantsToPurchaseCommonStockExpiring2025Member_e3429e1c-c148-45d3-9777-75fcd4e9f49a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_a8538a70-ff4a-4562-a566-633adf9f709a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentType_a8538a70-ff4a-4562-a566-633adf9f709a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentAnnualReport_d65d2aa5-9c01-4b8f-850a-b38dff16f6cd" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentAnnualReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentAnnualReport_d65d2aa5-9c01-4b8f-850a-b38dff16f6cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_29909ec7-1aec-4cc1-904a-2a93a6400538" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentPeriodEndDate_29909ec7-1aec-4cc1-904a-2a93a6400538" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_3338a3d4-f0e1-4fbd-88fc-29b2eb4f883b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_CurrentFiscalYearEndDate_3338a3d4-f0e1-4fbd-88fc-29b2eb4f883b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_0f6cd318-7333-4a2a-a726-59f54599ee03" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentTransitionReport_0f6cd318-7333-4a2a-a726-59f54599ee03" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_c2b7e328-c336-463d-a7c6-df8f18132bda" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityFileNumber_c2b7e328-c336-463d-a7c6-df8f18132bda" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_50651fd6-0382-46c1-8e4d-00770980bfbf" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityRegistrantName_50651fd6-0382-46c1-8e4d-00770980bfbf" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_6a272318-218c-487c-b68d-5a5093f17218" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityIncorporationStateCountryCode_6a272318-218c-487c-b68d-5a5093f17218" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_9df79446-d1f9-420c-bd0d-f1a0a04af5e9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityTaxIdentificationNumber_9df79446-d1f9-420c-bd0d-f1a0a04af5e9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_8f6349ce-d43a-4a33-b601-e4a01076a3db" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityAddressAddressLine1_8f6349ce-d43a-4a33-b601-e4a01076a3db" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_b0752e47-778e-4ee4-bd26-1191bbf1ddce" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityAddressCityOrTown_b0752e47-778e-4ee4-bd26-1191bbf1ddce" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_95f265a3-396d-45a6-ba4a-3d4e0b2a9317" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityAddressStateOrProvince_95f265a3-396d-45a6-ba4a-3d4e0b2a9317" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_bfe97894-b0d7-4014-a84d-9ab31579626e" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityAddressPostalZipCode_bfe97894-b0d7-4014-a84d-9ab31579626e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_d5d4ed3b-d23f-4853-b588-201e1d22d119" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_CityAreaCode_d5d4ed3b-d23f-4853-b588-201e1d22d119" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_bf82d12e-7a9c-4d39-bf90-97b435dcc600" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_LocalPhoneNumber_bf82d12e-7a9c-4d39-bf90-97b435dcc600" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_671e6062-85d7-4bc3-ba71-c6afc7b43b2c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_Security12bTitle_671e6062-85d7-4bc3-ba71-c6afc7b43b2c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_50ce8862-ffbc-431b-8b0f-d7c00e2f2c3d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_TradingSymbol_50ce8862-ffbc-431b-8b0f-d7c00e2f2c3d" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_7575f899-e965-414e-bda9-360789ba02a5" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_SecurityExchangeName_7575f899-e965-414e-bda9-360789ba02a5" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12gTitle_1f20a439-8656-4232-ab70-f6bd31082736" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12gTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_Security12gTitle_1f20a439-8656-4232-ab70-f6bd31082736" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityWellKnownSeasonedIssuer_4e231225-dbb3-4f86-977d-89933ce5b1fd" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityWellKnownSeasonedIssuer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityWellKnownSeasonedIssuer_4e231225-dbb3-4f86-977d-89933ce5b1fd" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityVoluntaryFilers_04893efe-4699-4dd0-a3aa-47b03e4b0b0c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityVoluntaryFilers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityVoluntaryFilers_04893efe-4699-4dd0-a3aa-47b03e4b0b0c" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_343775d5-5a55-4da9-abf9-00efe4b7455f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityCurrentReportingStatus_343775d5-5a55-4da9-abf9-00efe4b7455f" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_2806c99c-3983-4717-bca7-3f1317bff528" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityInteractiveDataCurrent_2806c99c-3983-4717-bca7-3f1317bff528" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_88d3e413-7368-4091-8844-5d40d05f4735" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityFilerCategory_88d3e413-7368-4091-8844-5d40d05f4735" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_ddc1d3b6-32f0-4f85-b483-dad2b754687c" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntitySmallBusiness_ddc1d3b6-32f0-4f85-b483-dad2b754687c" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_53f671dd-7379-4aaa-be5d-81b71afdfcaa" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityEmergingGrowthCompany_53f671dd-7379-4aaa-be5d-81b71afdfcaa" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_IcfrAuditorAttestationFlag_1a77d00b-4506-4761-a3cc-6bc4aff4b470" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_IcfrAuditorAttestationFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_IcfrAuditorAttestationFlag_1a77d00b-4506-4761-a3cc-6bc4aff4b470" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFinStmtErrorCorrectionFlag_ac29a550-39b2-487f-a373-d919aec769f8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFinStmtErrorCorrectionFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentFinStmtErrorCorrectionFlag_ac29a550-39b2-487f-a373-d919aec769f8" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_a006fc67-872e-441c-8ce5-7769fb6553a3" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityShellCompany_a006fc67-872e-441c-8ce5-7769fb6553a3" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityPublicFloat_be8b47c2-b3d3-48d7-9ab2-d4095801ba1d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityPublicFloat"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityPublicFloat_be8b47c2-b3d3-48d7-9ab2-d4095801ba1d" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_68d19e38-1e61-4dfa-9c11-0a3e488185d1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_68d19e38-1e61-4dfa-9c11-0a3e488185d1" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentsIncorporatedByReferenceTextBlock_d947a36c-c679-41fb-b795-0d9e25cd64ca" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentsIncorporatedByReferenceTextBlock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentsIncorporatedByReferenceTextBlock_d947a36c-c679-41fb-b795-0d9e25cd64ca" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_765db0ef-0a9f-4dea-8035-7fa7f86f96eb" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_EntityCentralIndexKey_765db0ef-0a9f-4dea-8035-7fa7f86f96eb" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_fc90e98f-a9e8-4f49-babc-a47d78a56fb3" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentFiscalYearFocus_fc90e98f-a9e8-4f49-babc-a47d78a56fb3" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_d39c113e-c941-4214-8567-c98f0a58d810" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_DocumentFiscalPeriodFocus_d39c113e-c941-4214-8567-c98f0a58d810" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_560fde71-1ed3-4da6-900c-3c37faf057e8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_98dffbdc-ef01-4cc8-b76a-660b0937acf0" xlink:to="loc_dei_AmendmentFlag_560fde71-1ed3-4da6-900c-3c37faf057e8" xlink:type="arc" order="35"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="oust-20241231.xsd#CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://ouster.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_047611ff-884e-4262-bc53-0130c5c8ce55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_92abcc2b-af21-4bd8-863e-ec4ac224dd9f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_047611ff-884e-4262-bc53-0130c5c8ce55" xlink:to="loc_us-gaap_StatementTable_92abcc2b-af21-4bd8-863e-ec4ac224dd9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_a93a3416-8ee9-4b7a-b32c-cc61a239db5b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_92abcc2b-af21-4bd8-863e-ec4ac224dd9f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_a93a3416-8ee9-4b7a-b32c-cc61a239db5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a93a3416-8ee9-4b7a-b32c-cc61a239db5b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a93a3416-8ee9-4b7a-b32c-cc61a239db5b" xlink:to="loc_us-gaap_EquityComponentDomain_a93a3416-8ee9-4b7a-b32c-cc61a239db5b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_a93a3416-8ee9-4b7a-b32c-cc61a239db5b" xlink:to="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7ef1c832-d4ff-4ac9-99b9-1fe92880c74b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:to="loc_us-gaap_CommonStockMember_7ef1c832-d4ff-4ac9-99b9-1fe92880c74b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_2c09dc30-c346-4e6b-88c9-f386143f3ea9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_2c09dc30-c346-4e6b-88c9-f386143f3ea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_b42d2808-2008-42db-8f95-3b6e54e112e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:to="loc_us-gaap_RetainedEarningsMember_b42d2808-2008-42db-8f95-3b6e54e112e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_f60236b8-09d8-4dc0-a84b-ebcf394e584f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1742f194-448f-4f41-877c-413569c379e7" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_f60236b8-09d8-4dc0-a84b-ebcf394e584f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_047611ff-884e-4262-bc53-0130c5c8ce55" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_2465f798-6231-4e09-960e-f7daab83cac4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_2465f798-6231-4e09-960e-f7daab83cac4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_b5c341d3-5783-4b76-9ff3-1e4e878a6507" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockholdersEquity_b5c341d3-5783-4b76-9ff3-1e4e878a6507" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_17908060-0b98-45f3-8d17-4599d25b7bdb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_17908060-0b98-45f3-8d17-4599d25b7bdb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_05188aac-e69f-4600-b64a-9701f82cf05d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueAcquisitions_05188aac-e69f-4600-b64a-9701f82cf05d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesReverseStockSplits_822ebe4d-8cc5-4e4f-bb53-815513884686" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesReverseStockSplits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesReverseStockSplits_822ebe4d-8cc5-4e4f-bb53-815513884686" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8dec9b65-1af6-47ef-9abc-d18dc4a54303" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_8dec9b65-1af6-47ef-9abc-d18dc4a54303" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_ab3f6dc9-f9a5-482d-909f-faee3bb8392e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_ab3f6dc9-f9a5-482d-909f-faee3bb8392e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7ec79694-4336-4259-b6fd-53089e5cfc52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_7ec79694-4336-4259-b6fd-53089e5cfc52" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b3e1669c-00e4-428f-84b6-9bcd30d38d95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_b3e1669c-00e4-428f-84b6-9bcd30d38d95" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_2d53b50f-0b01-48f2-8dd5-3c9d7f94d67e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_2d53b50f-0b01-48f2-8dd5-3c9d7f94d67e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_d68cd972-6bd6-47d3-8483-d7dd212b3ac3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_d68cd972-6bd6-47d3-8483-d7dd212b3ac3" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_4719cd9c-b58c-4b8c-a6f4-2dabf70038ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings_4719cd9c-b58c-4b8c-a6f4-2dabf70038ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings_bb5a4fe6-ae0e-4d7d-80e3-78c0a57867cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings_bb5a4fe6-ae0e-4d7d-80e3-78c0a57867cf" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_d7081491-f043-4069-b754-47eaf1c625c1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_d7081491-f043-4069-b754-47eaf1c625c1" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_24cd7da4-0baa-49a5-a318-7d4ca488074e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_24cd7da4-0baa-49a5-a318-7d4ca488074e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_46ece0e5-3030-4493-80d0-1cdc9290458f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_46ece0e5-3030-4493-80d0-1cdc9290458f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_bf206598-8c31-4808-b591-98d5f47c0608" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_bf206598-8c31-4808-b591-98d5f47c0608" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_d751a592-78a1-430b-817c-6f71abb7548f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_StockAndWarrantsIssuedDuringPeriodValuePreferredStockAndWarrants_d751a592-78a1-430b-817c-6f71abb7548f" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions_ca58acba-b51d-4303-beb8-6431132fb5cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationAndExerciseOfStockOptions_ca58acba-b51d-4303-beb8-6431132fb5cb" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_72f8e7a3-f40f-485c-b2c6-86cb60769a41" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_72f8e7a3-f40f-485c-b2c6-86cb60769a41" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_d63d99a1-10db-42d3-a458-abee3e85d0d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_NetIncomeLoss_d63d99a1-10db-42d3-a458-abee3e85d0d1" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f4f992d3-d434-4bad-91d1-1f6470f970e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_93f125a3-57d1-46be-b00d-b365dd1342da" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_f4f992d3-d434-4bad-91d1-1f6470f970e5" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_7ae19a34-5c7b-4503-9858-1cd485f34cce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2bcb9800-afd1-4b81-82ee-4bea89e14a53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/DescriptionofBusinessandBasisofPresentationDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#DescriptionofBusinessandBasisofPresentationDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/DescriptionofBusinessandBasisofPresentationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_e4d244a2-10c2-4725-afdf-22964eb138d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_e4d244a2-10c2-4725-afdf-22964eb138d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_6d0f65a9-217f-4c92-8cb3-ac93e6827069" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_e4d244a2-10c2-4725-afdf-22964eb138d3" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_6d0f65a9-217f-4c92-8cb3-ac93e6827069" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6d0f65a9-217f-4c92-8cb3-ac93e6827069_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_6d0f65a9-217f-4c92-8cb3-ac93e6827069" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_6d0f65a9-217f-4c92-8cb3-ac93e6827069_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7ef60ae2-c557-41fe-ab96-0510a791cc5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_6d0f65a9-217f-4c92-8cb3-ac93e6827069" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7ef60ae2-c557-41fe-ab96-0510a791cc5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AtTheMarketProgramMember_29a1774b-2450-4ce5-bd91-ff5444a75ff3" xlink:href="oust-20241231.xsd#oust_AtTheMarketProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_7ef60ae2-c557-41fe-ab96-0510a791cc5f" xlink:to="loc_oust_AtTheMarketProgramMember_29a1774b-2450-4ce5-bd91-ff5444a75ff3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_812270cc-1e10-49f1-85ba-df4aacfa007d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_e4d244a2-10c2-4725-afdf-22964eb138d3" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_812270cc-1e10-49f1-85ba-df4aacfa007d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_812270cc-1e10-49f1-85ba-df4aacfa007d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_812270cc-1e10-49f1-85ba-df4aacfa007d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_812270cc-1e10-49f1-85ba-df4aacfa007d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_4c6d5bf8-3f83-4fa9-a644-cb74d40aac8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_812270cc-1e10-49f1-85ba-df4aacfa007d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_4c6d5bf8-3f83-4fa9-a644-cb74d40aac8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CLAWarrantsMember_3de51b35-0a58-457a-9c54-f1a479c54ab7" xlink:href="oust-20241231.xsd#oust_CLAWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_4c6d5bf8-3f83-4fa9-a644-cb74d40aac8e" xlink:to="loc_oust_CLAWarrantsMember_3de51b35-0a58-457a-9c54-f1a479c54ab7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrivatePlacementMember_3f5e74c4-1044-4391-bd92-a5d875394b35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PrivatePlacementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_4c6d5bf8-3f83-4fa9-a644-cb74d40aac8e" xlink:to="loc_us-gaap_PrivatePlacementMember_3f5e74c4-1044-4391-bd92-a5d875394b35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightIssued_0f2b5719-eeb4-4122-bac9-fa1178d09a8a" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_ClassOfWarrantOrRightIssued_0f2b5719-eeb4-4122-bac9-fa1178d09a8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_b32aead5-0760-4e68-a75d-ab19f812329b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_b32aead5-0760-4e68-a75d-ab19f812329b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightConversionRatio_81c83a80-3562-431c-8527-76a96c398d07" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_ClassOfWarrantOrRightConversionRatio_81c83a80-3562-431c-8527-76a96c398d07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_NumberOfFractionalWarrantsIssued_277c7ba6-c335-4378-88de-e254a309704f" xlink:href="oust-20241231.xsd#oust_NumberOfFractionalWarrantsIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_NumberOfFractionalWarrantsIssued_277c7ba6-c335-4378-88de-e254a309704f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_149025bc-83e8-4c72-bf66-402ee23f5749" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_149025bc-83e8-4c72-bf66-402ee23f5749" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_67af151e-1f41-4bef-905a-1dcfb6333601" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsAndShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_CashCashEquivalentsAndShortTermInvestments_67af151e-1f41-4bef-905a-1dcfb6333601" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockAuthorizedAmount_097adc8a-4975-4724-ac2c-7099bc9274c7" xlink:href="oust-20241231.xsd#oust_SaleOfStockAuthorizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_SaleOfStockAuthorizedAmount_097adc8a-4975-4724-ac2c-7099bc9274c7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_26424dae-3c82-4b64-96b8-e139546b886f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_26424dae-3c82-4b64-96b8-e139546b886f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockWeightedAverageStockPricePerShare_0ba18189-613e-4f38-8a5c-f5bcfd1c56ca" xlink:href="oust-20241231.xsd#oust_SaleOfStockWeightedAverageStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_SaleOfStockWeightedAverageStockPricePerShare_0ba18189-613e-4f38-8a5c-f5bcfd1c56ca" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_30dde07b-4881-460a-bb1f-5275bbc0910b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_30dde07b-4881-460a-bb1f-5275bbc0910b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockRemainingAuthorizedAmount_2c65415c-b935-4882-a639-48609b1327ea" xlink:href="oust-20241231.xsd#oust_SaleOfStockRemainingAuthorizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_01d3df5f-9f03-4814-9671-2f104a7842cf" xlink:to="loc_oust_SaleOfStockRemainingAuthorizedAmount_2c65415c-b935-4882-a639-48609b1327ea" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#SummaryofSignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_b9a5724d-efaa-4e50-a39e-754e8e7f32d6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_f9ea0c0d-3aec-4113-a9ef-80ee3db55d8a" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_b9a5724d-efaa-4e50-a39e-754e8e7f32d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableMember_3fc64386-61e4-4eb4-a69f-eb8be4b9974a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_b9a5724d-efaa-4e50-a39e-754e8e7f32d6" xlink:to="loc_us-gaap_AccountsPayableMember_3fc64386-61e4-4eb4-a69f-eb8be4b9974a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_f97bf4a6-b4cb-4e8d-af16-660474c3eaae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_f97bf4a6-b4cb-4e8d-af16-660474c3eaae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_f97bf4a6-b4cb-4e8d-af16-660474c3eaae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_f97bf4a6-b4cb-4e8d-af16-660474c3eaae" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_f97bf4a6-b4cb-4e8d-af16-660474c3eaae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_0e01e6a3-181e-449c-adbd-576bff1571f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_f97bf4a6-b4cb-4e8d-af16-660474c3eaae" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_0e01e6a3-181e-449c-adbd-576bff1571f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierConcentrationRiskMember_af55349d-80b2-467e-a1a3-6d5f503df4e3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SupplierConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_0e01e6a3-181e-449c-adbd-576bff1571f2" xlink:to="loc_us-gaap_SupplierConcentrationRiskMember_af55349d-80b2-467e-a1a3-6d5f503df4e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_bb74cbbb-cae0-4dd1-9fd8-c885308972f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_bb74cbbb-cae0-4dd1-9fd8-c885308972f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_bb74cbbb-cae0-4dd1-9fd8-c885308972f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_bb74cbbb-cae0-4dd1-9fd8-c885308972f0" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_bb74cbbb-cae0-4dd1-9fd8-c885308972f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_673670d7-4b48-4738-92c7-6fc73899fe0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_bb74cbbb-cae0-4dd1-9fd8-c885308972f0" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_673670d7-4b48-4738-92c7-6fc73899fe0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SupplierAMember_87c6ed49-3905-4363-ae24-b784bcc9e74e" xlink:href="oust-20241231.xsd#oust_SupplierAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_673670d7-4b48-4738-92c7-6fc73899fe0c" xlink:to="loc_oust_SupplierAMember_87c6ed49-3905-4363-ae24-b784bcc9e74e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SupplierBMember_2d06aa0c-2c79-4b36-85ad-670ffa128d94" xlink:href="oust-20241231.xsd#oust_SupplierBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_673670d7-4b48-4738-92c7-6fc73899fe0c" xlink:to="loc_oust_SupplierBMember_2d06aa0c-2c79-4b36-85ad-670ffa128d94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:to="loc_srt_RangeAxis_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934" xlink:to="loc_srt_RangeMember_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_fafa421b-d765-4fb4-a4b1-2e537be566ef" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_66c2b5c7-ded9-4c28-bfc9-fc9318ec0934" xlink:to="loc_srt_RangeMember_fafa421b-d765-4fb4-a4b1-2e537be566ef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_14f1315d-e5cf-4321-991a-5fa9c1fc3597" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fafa421b-d765-4fb4-a4b1-2e537be566ef" xlink:to="loc_srt_MinimumMember_14f1315d-e5cf-4321-991a-5fa9c1fc3597" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_5af0e9c1-820b-4c12-ae5d-5e27fbe832db" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_fafa421b-d765-4fb4-a4b1-2e537be566ef" xlink:to="loc_srt_MaximumMember_5af0e9c1-820b-4c12-ae5d-5e27fbe832db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_003abfdd-2a1f-421c-8855-66cce7668cf7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_435f190d-cc20-4c23-8a20-1042f9ced3cd" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_003abfdd-2a1f-421c-8855-66cce7668cf7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_003abfdd-2a1f-421c-8855-66cce7668cf7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_003abfdd-2a1f-421c-8855-66cce7668cf7" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_003abfdd-2a1f-421c-8855-66cce7668cf7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_7bcf499d-e59f-45cf-9ba1-8c067216728f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_003abfdd-2a1f-421c-8855-66cce7668cf7" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_7bcf499d-e59f-45cf-9ba1-8c067216728f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PrivatePlacementWarrantsMember_1e8a557a-6c84-4541-adbc-067421461b97" xlink:href="oust-20241231.xsd#oust_PrivatePlacementWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_7bcf499d-e59f-45cf-9ba1-8c067216728f" xlink:to="loc_oust_PrivatePlacementWarrantsMember_1e8a557a-6c84-4541-adbc-067421461b97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_baac6060-c769-4c27-adac-ea0b85161f90" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_NumberOfReportableSegments_baac6060-c769-4c27-adac-ea0b85161f90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_3063c372-8b06-43df-9223-1f0299d5970d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_NumberOfOperatingSegments_3063c372-8b06-43df-9223-1f0299d5970d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ProductWarrantyTerm_021a4d3f-f90c-4909-b383-73aadb5e66d0" xlink:href="oust-20241231.xsd#oust_ProductWarrantyTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_ProductWarrantyTerm_021a4d3f-f90c-4909-b383-73aadb5e66d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesCommissionsAndFees_030a123b-971a-4f5d-9e7c-77373c44f906" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SalesCommissionsAndFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_SalesCommissionsAndFees_030a123b-971a-4f5d-9e7c-77373c44f906" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_331b5815-5cac-4391-ad33-0d5d347549e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_331b5815-5cac-4391-ad33-0d5d347549e1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdCommonStockPrice_61c882e0-5785-4533-a8aa-7d87fa63705e" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightRedemptionTermsThresholdCommonStockPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdCommonStockPrice_61c882e0-5785-4533-a8aa-7d87fa63705e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDays_4dfdad2a-047d-422b-9478-170e24c0be8a" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDays_4dfdad2a-047d-422b-9478-170e24c0be8a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDayPeriod_2c025868-e2ea-41a8-a1e0-0b1e177339a4" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDayPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_ClassOfWarrantOrRightRedemptionTermsThresholdTradingDayPeriod_2c025868-e2ea-41a8-a1e0-0b1e177339a4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightRedemptionTermsNumberOfBusinessDaysBeforeNoticeOfRedemption_2c6e9664-7787-4ab1-a169-f80d211c1d9a" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightRedemptionTermsNumberOfBusinessDaysBeforeNoticeOfRedemption"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_ClassOfWarrantOrRightRedemptionTermsNumberOfBusinessDaysBeforeNoticeOfRedemption_2c6e9664-7787-4ab1-a169-f80d211c1d9a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CashCashEquivalentsAndRestrictedCashFDICInsuredAmount_5567524f-e297-41a3-ae21-a847cadd89f4" xlink:href="oust-20241231.xsd#oust_CashCashEquivalentsAndRestrictedCashFDICInsuredAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_CashCashEquivalentsAndRestrictedCashFDICInsuredAmount_5567524f-e297-41a3-ae21-a847cadd89f4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CashCashEquivalentsAndRestrictedCashUninsuredAmount_59479f04-9fa9-4f4c-8d99-082821b2df84" xlink:href="oust-20241231.xsd#oust_CashCashEquivalentsAndRestrictedCashUninsuredAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_oust_CashCashEquivalentsAndRestrictedCashUninsuredAmount_59479f04-9fa9-4f4c-8d99-082821b2df84" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ThresholdPeriodPastDueForWriteoffOfTradeAccountsReceivable_0465dc20-e1d4-40f2-975b-8baad9642e73" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ThresholdPeriodPastDueForWriteoffOfTradeAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_ThresholdPeriodPastDueForWriteoffOfTradeAccountsReceivable_0465dc20-e1d4-40f2-975b-8baad9642e73" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_17463dbd-ea72-4ef1-9e40-504daeb71644" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_17463dbd-ea72-4ef1-9e40-504daeb71644" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_2e6394a7-01d6-4331-beee-c54b56a5edcd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_431b5200-4936-4bf0-9177-f80621d86e05" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_2e6394a7-01d6-4331-beee-c54b56a5edcd" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_275965b5-3865-4a2d-9787-cdb797fef24f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_275965b5-3865-4a2d-9787-cdb797fef24f" xlink:to="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_b533b222-1508-4ed7-b9f9-96af39b548fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_b533b222-1508-4ed7-b9f9-96af39b548fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_b533b222-1508-4ed7-b9f9-96af39b548fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_b533b222-1508-4ed7-b9f9-96af39b548fa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_b533b222-1508-4ed7-b9f9-96af39b548fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_750539ac-2004-4ff7-ad6b-29e1262eccf3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_b533b222-1508-4ed7-b9f9-96af39b548fa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_750539ac-2004-4ff7-ad6b-29e1262eccf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_7cf01b0c-4b2d-4c08-a9b2-c3e364ee380b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_750539ac-2004-4ff7-ad6b-29e1262eccf3" xlink:to="loc_us-gaap_AccountsReceivableMember_7cf01b0c-4b2d-4c08-a9b2-c3e364ee380b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsTotalMember_7e997c64-0fc6-49ed-b5d0-0204c19682af" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfGoodsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_750539ac-2004-4ff7-ad6b-29e1262eccf3" xlink:to="loc_us-gaap_CostOfGoodsTotalMember_7e997c64-0fc6-49ed-b5d0-0204c19682af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_05ec5343-d799-4c31-9fc4-fe3d1ff0933f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_05ec5343-d799-4c31-9fc4-fe3d1ff0933f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_05ec5343-d799-4c31-9fc4-fe3d1ff0933f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_05ec5343-d799-4c31-9fc4-fe3d1ff0933f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_05ec5343-d799-4c31-9fc4-fe3d1ff0933f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_977e7186-f75e-4bb2-8ccf-9170330fb7cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_05ec5343-d799-4c31-9fc4-fe3d1ff0933f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_977e7186-f75e-4bb2-8ccf-9170330fb7cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_55edf910-e708-40e1-905d-96c47d828d23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_977e7186-f75e-4bb2-8ccf-9170330fb7cc" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_55edf910-e708-40e1-905d-96c47d828d23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierConcentrationRiskMember_5b8a01a2-381d-4630-b66e-4b10db19ec37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SupplierConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_977e7186-f75e-4bb2-8ccf-9170330fb7cc" xlink:to="loc_us-gaap_SupplierConcentrationRiskMember_5b8a01a2-381d-4630-b66e-4b10db19ec37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_8ebacde5-391b-4b20-ad4e-c428110b9257" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:to="loc_srt_MajorCustomersAxis_8ebacde5-391b-4b20-ad4e-c428110b9257" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_8ebacde5-391b-4b20-ad4e-c428110b9257_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_8ebacde5-391b-4b20-ad4e-c428110b9257" xlink:to="loc_srt_NameOfMajorCustomerDomain_8ebacde5-391b-4b20-ad4e-c428110b9257_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_2e0ab282-d733-4301-96e5-9f27b805de98" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_8ebacde5-391b-4b20-ad4e-c428110b9257" xlink:to="loc_srt_NameOfMajorCustomerDomain_2e0ab282-d733-4301-96e5-9f27b805de98" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CustomerAMember_dbd86683-3e9c-4d83-ac66-2531406cca5f" xlink:href="oust-20241231.xsd#oust_CustomerAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_2e0ab282-d733-4301-96e5-9f27b805de98" xlink:to="loc_oust_CustomerAMember_dbd86683-3e9c-4d83-ac66-2531406cca5f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CustomerBMember_27895976-8d85-4d63-879a-f8a2b96470f7" xlink:href="oust-20241231.xsd#oust_CustomerBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_2e0ab282-d733-4301-96e5-9f27b805de98" xlink:to="loc_oust_CustomerBMember_27895976-8d85-4d63-879a-f8a2b96470f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_172b649f-72c6-4f76-b155-90ad5970429c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_ce083b06-beee-40f2-817e-117cf00cf17c" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_172b649f-72c6-4f76-b155-90ad5970429c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_172b649f-72c6-4f76-b155-90ad5970429c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_172b649f-72c6-4f76-b155-90ad5970429c" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_172b649f-72c6-4f76-b155-90ad5970429c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_b9f353f4-b66d-439d-8f90-60dbf80f1acb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_172b649f-72c6-4f76-b155-90ad5970429c" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_b9f353f4-b66d-439d-8f90-60dbf80f1acb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SupplierAMember_ef073106-d749-4e0e-9290-b4f4e2a55cc3" xlink:href="oust-20241231.xsd#oust_SupplierAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_b9f353f4-b66d-439d-8f90-60dbf80f1acb" xlink:to="loc_oust_SupplierAMember_ef073106-d749-4e0e-9290-b4f4e2a55cc3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SupplierBMember_cd12f880-0a4d-491c-af6b-efb5e95ca6ec" xlink:href="oust-20241231.xsd#oust_SupplierBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_b9f353f4-b66d-439d-8f90-60dbf80f1acb" xlink:to="loc_oust_SupplierBMember_cd12f880-0a4d-491c-af6b-efb5e95ca6ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_554f8a1d-3942-41a3-b1fa-90038dfc07ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_275965b5-3865-4a2d-9787-cdb797fef24f" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_554f8a1d-3942-41a3-b1fa-90038dfc07ee" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BusinessCombinationandRelatedTransactionsNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BusinessCombinationandRelatedTransactionsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BusinessCombinationandRelatedTransactionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e5a5eac9-e862-40b7-bc26-b07bc700e51f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e5a5eac9-e862-40b7-bc26-b07bc700e51f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_dc0a9161-21bc-4eb6-8242-df646f9ec7bf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e5a5eac9-e862-40b7-bc26-b07bc700e51f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_dc0a9161-21bc-4eb6-8242-df646f9ec7bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dc0a9161-21bc-4eb6-8242-df646f9ec7bf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dc0a9161-21bc-4eb6-8242-df646f9ec7bf" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_dc0a9161-21bc-4eb6-8242-df646f9ec7bf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d458a181-ac3c-4bda-a805-46d2a4329fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_dc0a9161-21bc-4eb6-8242-df646f9ec7bf" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d458a181-ac3c-4bda-a805-46d2a4329fb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_f02e3931-6f76-464c-a7c6-3d0a37343bb2" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d458a181-ac3c-4bda-a805-46d2a4329fb7" xlink:to="loc_oust_VelodyneLidarIncMember_f02e3931-6f76-464c-a7c6-3d0a37343bb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2cecaa17-8176-4606-86eb-3f7df01398b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e5a5eac9-e862-40b7-bc26-b07bc700e51f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2cecaa17-8176-4606-86eb-3f7df01398b3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2cecaa17-8176-4606-86eb-3f7df01398b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2cecaa17-8176-4606-86eb-3f7df01398b3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2cecaa17-8176-4606-86eb-3f7df01398b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1dff3330-ca23-4852-86e0-f36f8a23b851" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2cecaa17-8176-4606-86eb-3f7df01398b3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1dff3330-ca23-4852-86e0-f36f8a23b851" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_492c3fc5-1bdc-4577-a669-ef14ef7cf368" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1dff3330-ca23-4852-86e0-f36f8a23b851" xlink:to="loc_us-gaap_CustomerRelationshipsMember_492c3fc5-1bdc-4577-a669-ef14ef7cf368" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_b373503b-a037-4109-bce9-6101a19f2608" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e5a5eac9-e862-40b7-bc26-b07bc700e51f" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_b373503b-a037-4109-bce9-6101a19f2608" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_b373503b-a037-4109-bce9-6101a19f2608_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_b373503b-a037-4109-bce9-6101a19f2608" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_b373503b-a037-4109-bce9-6101a19f2608_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_0ff48507-7f3b-4f17-9ec5-cc8fe00c7fdb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_b373503b-a037-4109-bce9-6101a19f2608" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_0ff48507-7f3b-4f17-9ec5-cc8fe00c7fdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AmazonWarrantMember_1dc040fe-00c5-4a3e-98e2-fb0ffe7375b0" xlink:href="oust-20241231.xsd#oust_AmazonWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_0ff48507-7f3b-4f17-9ec5-cc8fe00c7fdb" xlink:to="loc_oust_AmazonWarrantMember_1dc040fe-00c5-4a3e-98e2-fb0ffe7375b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationExchangeRatio_a6d975ca-f36b-443b-963a-7fd572475a69" xlink:href="oust-20241231.xsd#oust_BusinessCombinationExchangeRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_oust_BusinessCombinationExchangeRatio_a6d975ca-f36b-443b-963a-7fd572475a69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ebfc14d7-f7f4-4e27-a87f-2eda31b9878b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_ebfc14d7-f7f4-4e27-a87f-2eda31b9878b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_ba4a1061-35a8-4ecc-b17d-2be91bb1a54e" xlink:href="oust-20241231.xsd#oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_ba4a1061-35a8-4ecc-b17d-2be91bb1a54e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_d4c99a3b-4e1a-4b1a-b287-82473791dbce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationAcquisitionRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_us-gaap_BusinessCombinationAcquisitionRelatedCosts_d4c99a3b-4e1a-4b1a-b287-82473791dbce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_8abc93dd-a796-4bb4-b066-b332eb3a0fd7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_8abc93dd-a796-4bb4-b066-b332eb3a0fd7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_e8d1311c-5a57-4a7d-bd15-9c2256368f45" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_243c7849-8f25-4fd5-ab8b-b51b10afc995" xlink:to="loc_us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual_e8d1311c-5a57-4a7d-bd15-9c2256368f45" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BusinessCombinationandRelatedTransactionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_c178e489-08e9-47ab-a931-495086b179d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_c178e489-08e9-47ab-a931-495086b179d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_17f31559-bc83-4ff5-b704-a8f7b17dca89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_c178e489-08e9-47ab-a931-495086b179d4" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_17f31559-bc83-4ff5-b704-a8f7b17dca89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_17f31559-bc83-4ff5-b704-a8f7b17dca89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_17f31559-bc83-4ff5-b704-a8f7b17dca89" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_17f31559-bc83-4ff5-b704-a8f7b17dca89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9eeedb27-0944-4064-843c-669dc2aa4d88" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_17f31559-bc83-4ff5-b704-a8f7b17dca89" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9eeedb27-0944-4064-843c-669dc2aa4d88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_7b6eae7a-a5d3-426e-abf6-de3d9821b092" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_9eeedb27-0944-4064-843c-669dc2aa4d88" xlink:to="loc_oust_VelodyneLidarIncMember_7b6eae7a-a5d3-426e-abf6-de3d9821b092" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_906fae41-348e-4d3d-a40c-246ddd54afb2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_906fae41-348e-4d3d-a40c-246ddd54afb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_6c61b9ca-540a-48b3-8fd6-4bfce1897d34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_6c61b9ca-540a-48b3-8fd6-4bfce1897d34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermInvestments_56503c2e-ca26-45cc-af0f-23c9ccf404fe" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedShortTermInvestments_56503c2e-ca26-45cc-af0f-23c9ccf404fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_455f0c11-1a27-4170-9641-a5554ccf85e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_455f0c11-1a27-4170-9641-a5554ccf85e5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_e3691439-726d-4384-9321-c936e4c1f4f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_e3691439-726d-4384-9321-c936e4c1f4f1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_892098f7-ad12-4119-ba57-d9efd120903d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_892098f7-ad12-4119-ba57-d9efd120903d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerAssetAfterAllowanceForCreditLossNoncurrent_7cc8e7d1-ac84-44d1-b55a-1dd5d6fc6847" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerAssetAfterAllowanceForCreditLossNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerAssetAfterAllowanceForCreditLossNoncurrent_7cc8e7d1-ac84-44d1-b55a-1dd5d6fc6847" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_29595d62-cc90-4520-9832-82165622376d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_29595d62-cc90-4520-9832-82165622376d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets_0e6d2044-5337-4f07-b9c6-08b3ae4f96ef" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseRightOfUseAssets_0e6d2044-5337-4f07-b9c6-08b3ae4f96ef" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_5b5c078c-fc72-4af8-b514-ca5edfe70314" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_5b5c078c-fc72-4af8-b514-ca5edfe70314" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_522851ec-fd11-4c5f-9ffe-7435b5511496" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_522851ec-fd11-4c5f-9ffe-7435b5511496" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_14201981-8728-4d26-b89d-9165d832a9bf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_14201981-8728-4d26-b89d-9165d832a9bf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedAndOtherCurrentLiabilities_73ec57f3-f3a7-4e32-81f6-05c8904942e6" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedAndOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccruedAndOtherCurrentLiabilities_73ec57f3-f3a7-4e32-81f6-05c8904942e6" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityCurrent_7bd8037f-20f4-4b74-974b-ceb5b771f58e" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityCurrent_7bd8037f-20f4-4b74-974b-ceb5b771f58e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent_8e05a807-3768-474e-b811-3de5b40c44aa" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityCurrent_8e05a807-3768-474e-b811-3de5b40c44aa" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent_8388ba4d-b900-4372-80c4-04ac1dbd8f12" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOperatingLeaseLiabilityNoncurrent_8388ba4d-b900-4372-80c4-04ac1dbd8f12" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityNoncurrent_91737bb1-874a-49de-bc46-1768f4593a16" xlink:href="oust-20241231.xsd#oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_oust_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedContractWithCustomerLiabilityNoncurrent_91737bb1-874a-49de-bc46-1768f4593a16" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_2c757697-fd5b-4d42-882a-1c2aef82edff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNetAbstract_205748ed-c3a3-4e2b-a6ff-988523c61eff" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_2c757697-fd5b-4d42-882a-1c2aef82edff" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_57614f82-b915-49f3-82a9-b113c3390cce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_57614f82-b915-49f3-82a9-b113c3390cce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_5cca7ffa-fe32-4761-aee5-e16f5f08cdbb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_Goodwill_5cca7ffa-fe32-4761-aee5-e16f5f08cdbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_dca0e0b7-5d05-4e92-a208-869f23fecfcd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_26c9e4af-6990-47d7-8fe5-106232136aeb" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_dca0e0b7-5d05-4e92-a208-869f23fecfcd" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofIdentifiedIntangibleAssetsAcquiredandtheirEstimatedUsefulLivesDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BusinessCombinationandRelatedTransactionsScheduleofIdentifiedIntangibleAssetsAcquiredandtheirEstimatedUsefulLivesDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofIdentifiedIntangibleAssetsAcquiredandtheirEstimatedUsefulLivesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_14f0da65-509b-4283-8a97-41782f843d46" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e4d1d9e8-9c18-4785-96cd-4e5086ae05f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_14f0da65-509b-4283-8a97-41782f843d46" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e4d1d9e8-9c18-4785-96cd-4e5086ae05f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e4d1d9e8-9c18-4785-96cd-4e5086ae05f3" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4f5fd96c-e090-4ab1-83de-096b4e038650" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a7b8fb98-bd05-414a-8f63-2d54dcd26c2d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4f5fd96c-e090-4ab1-83de-096b4e038650" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_1f495ee4-2a9f-411e-b960-4b08bd9873e1" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4f5fd96c-e090-4ab1-83de-096b4e038650" xlink:to="loc_oust_VelodyneLidarIncMember_1f495ee4-2a9f-411e-b960-4b08bd9873e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e4d1d9e8-9c18-4785-96cd-4e5086ae05f3" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_219465fb-f9b8-4f63-8513-4a3750dc91b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_71e5f1a0-5f73-4d4d-9d83-669f5f527bd5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_219465fb-f9b8-4f63-8513-4a3750dc91b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_DevelopedTechnologyHardwareMember_9b5f2e6f-49e3-48cb-a9b2-637ee0ad684e" xlink:href="oust-20241231.xsd#oust_DevelopedTechnologyHardwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_219465fb-f9b8-4f63-8513-4a3750dc91b5" xlink:to="loc_oust_DevelopedTechnologyHardwareMember_9b5f2e6f-49e3-48cb-a9b2-637ee0ad684e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_DevelopedTechnologySoftwareMember_800270dd-a266-483a-ab86-d5e54f219544" xlink:href="oust-20241231.xsd#oust_DevelopedTechnologySoftwareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_219465fb-f9b8-4f63-8513-4a3750dc91b5" xlink:to="loc_oust_DevelopedTechnologySoftwareMember_800270dd-a266-483a-ab86-d5e54f219544" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_11d91fc0-93c1-47d9-a26c-00344c993253" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_219465fb-f9b8-4f63-8513-4a3750dc91b5" xlink:to="loc_us-gaap_CustomerRelationshipsMember_11d91fc0-93c1-47d9-a26c-00344c993253" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_f8029245-ce4a-4d92-a442-5f31c430e2cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_14f0da65-509b-4283-8a97-41782f843d46" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_f8029245-ce4a-4d92-a442-5f31c430e2cd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_e1a4a2a6-9e13-4943-9ca4-c22990e135ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_14f0da65-509b-4283-8a97-41782f843d46" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_e1a4a2a6-9e13-4943-9ca4-c22990e135ab" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_401eb932-6098-45a7-89ab-eed25213b228" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e427fc84-2ca8-48dc-958d-9cc73bd6057f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_401eb932-6098-45a7-89ab-eed25213b228" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e427fc84-2ca8-48dc-958d-9cc73bd6057f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_e427fc84-2ca8-48dc-958d-9cc73bd6057f" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bee02b9e-fd04-4598-9e4e-17152b596926" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e4b36b7d-bbbc-4688-a6c7-666e0a1363b6" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bee02b9e-fd04-4598-9e4e-17152b596926" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_b86b48d7-8757-45aa-8fb0-9bc766afd2af" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_bee02b9e-fd04-4598-9e4e-17152b596926" xlink:to="loc_oust_VelodyneLidarIncMember_b86b48d7-8757-45aa-8fb0-9bc766afd2af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_90c5ff72-d6c1-435a-bad5-959b8c586ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_401eb932-6098-45a7-89ab-eed25213b228" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_90c5ff72-d6c1-435a-bad5-959b8c586ba0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_6f746550-bbdd-4e32-bcd0-a634d431d80f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_401eb932-6098-45a7-89ab-eed25213b228" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_6f746550-bbdd-4e32-bcd0-a634d431d80f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationAdjustmentsDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationAdjustmentsDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BusinessCombinationandRelatedTransactionsScheduleofBusinessAcquisitionProFormaInformationAdjustmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_cb1f470d-ed3e-4272-ab1b-1474f7f9b87a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9e2ddb1b-e736-470a-a5ef-57a90ef66259" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb1f470d-ed3e-4272-ab1b-1474f7f9b87a" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9e2ddb1b-e736-470a-a5ef-57a90ef66259" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_d39c78ae-9215-42ad-8a1d-80340fde96d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9e2ddb1b-e736-470a-a5ef-57a90ef66259" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_d39c78ae-9215-42ad-8a1d-80340fde96d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d39c78ae-9215-42ad-8a1d-80340fde96d2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d39c78ae-9215-42ad-8a1d-80340fde96d2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_d39c78ae-9215-42ad-8a1d-80340fde96d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_595147be-6c8c-4fb6-adb9-3617ba5f75fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_d39c78ae-9215-42ad-8a1d-80340fde96d2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_595147be-6c8c-4fb6-adb9-3617ba5f75fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_f1acc3f3-dcb1-4265-9cfa-83527acf1bbe" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_595147be-6c8c-4fb6-adb9-3617ba5f75fb" xlink:to="loc_oust_VelodyneLidarIncMember_f1acc3f3-dcb1-4265-9cfa-83527acf1bbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentAxis_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_9e2ddb1b-e736-470a-a5ef-57a90ef66259" xlink:to="loc_us-gaap_NonrecurringAdjustmentAxis_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonrecurringAdjustmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_NonrecurringAdjustmentAxis_33df23e6-4fd3-4f99-892d-1b5c8c6d0a6b" xlink:to="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_FairValueAdjustmentToIntangibleAssetsMember_60d84879-2854-4cf4-9e19-32a5afb31792" xlink:href="oust-20241231.xsd#oust_FairValueAdjustmentToIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_oust_FairValueAdjustmentToIntangibleAssetsMember_60d84879-2854-4cf4-9e19-32a5afb31792" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquisitionRelatedCostsMember_b65c0c69-c9c2-4c96-8423-7a72f5841a02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcquisitionRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_us-gaap_AcquisitionRelatedCostsMember_b65c0c69-c9c2-4c96-8423-7a72f5841a02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AdjustmentToRevenueRelatedToVestingOfWarrantMember_399dafc3-3863-4df9-88fb-285498c6fbaa" xlink:href="oust-20241231.xsd#oust_AdjustmentToRevenueRelatedToVestingOfWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_oust_AdjustmentToRevenueRelatedToVestingOfWarrantMember_399dafc3-3863-4df9-88fb-285498c6fbaa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AdjustmentToExpensesRelatedToVestingOfWarrantMember_b24ee3c6-b47b-47b7-a52c-ebe9340ee6ff" xlink:href="oust-20241231.xsd#oust_AdjustmentToExpensesRelatedToVestingOfWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_oust_AdjustmentToExpensesRelatedToVestingOfWarrantMember_b24ee3c6-b47b-47b7-a52c-ebe9340ee6ff" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationExpenseAdjustmentMember_c8f690f3-f71b-4de6-8774-0cc21e8de654" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationExpenseAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_oust_ShareBasedCompensationExpenseAdjustmentMember_c8f690f3-f71b-4de6-8774-0cc21e8de654" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SeverancePaymentsAdjustmentsMember_c8300b45-56f3-4d6f-b723-e78a0e5f9822" xlink:href="oust-20241231.xsd#oust_SeverancePaymentsAdjustmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonrecurringAdjustmentDomain_bac0df07-a035-47be-93df-265187c568a9" xlink:to="loc_oust_SeverancePaymentsAdjustmentsMember_c8300b45-56f3-4d6f-b723-e78a0e5f9822" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_82ef6a93-5539-4e5c-bfbe-487ae0480544" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_cb1f470d-ed3e-4272-ab1b-1474f7f9b87a" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_82ef6a93-5539-4e5c-bfbe-487ae0480544" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/FairValueofFinancialInstrumentsScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#FairValueofFinancialInstrumentsScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/FairValueofFinancialInstrumentsScheduleofFairValueAssetsandLiabilitiesMeasuredonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d7228f47-45a2-48a9-ab3c-2a424e4a18e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d7228f47-45a2-48a9-ab3c-2a424e4a18e4" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_5da9f36c-59e1-41d0-9e13-f06408296dce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_5da9f36c-59e1-41d0-9e13-f06408296dce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_5da9f36c-59e1-41d0-9e13-f06408296dce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_5da9f36c-59e1-41d0-9e13-f06408296dce" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_5da9f36c-59e1-41d0-9e13-f06408296dce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_83698c29-efdc-46f0-adb0-aba21a003f4a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_5da9f36c-59e1-41d0-9e13-f06408296dce" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_83698c29-efdc-46f0-adb0-aba21a003f4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_91e9de98-2aa7-460e-912b-e706a3acd95e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_83698c29-efdc-46f0-adb0-aba21a003f4a" xlink:to="loc_us-gaap_MoneyMarketFundsMember_91e9de98-2aa7-460e-912b-e706a3acd95e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_10cbc73f-39ea-4459-8fca-313fe31f460d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_83698c29-efdc-46f0-adb0-aba21a003f4a" xlink:to="loc_us-gaap_CommercialPaperMember_10cbc73f-39ea-4459-8fca-313fe31f460d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_be3801c1-0a4a-4b0d-9cef-50f02e40c410" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_be3801c1-0a4a-4b0d-9cef-50f02e40c410" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_be3801c1-0a4a-4b0d-9cef-50f02e40c410_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_be3801c1-0a4a-4b0d-9cef-50f02e40c410" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_be3801c1-0a4a-4b0d-9cef-50f02e40c410_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_217f9ca5-6803-4bfa-a484-0805130a43ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_be3801c1-0a4a-4b0d-9cef-50f02e40c410" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_217f9ca5-6803-4bfa-a484-0805130a43ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_aa0721e3-44a0-4ae1-9031-e0033e39fdd5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_217f9ca5-6803-4bfa-a484-0805130a43ac" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_aa0721e3-44a0-4ae1-9031-e0033e39fdd5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_579b4f71-84be-48ca-9d1d-5b4fbe16bce3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_579b4f71-84be-48ca-9d1d-5b4fbe16bce3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_579b4f71-84be-48ca-9d1d-5b4fbe16bce3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_579b4f71-84be-48ca-9d1d-5b4fbe16bce3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_579b4f71-84be-48ca-9d1d-5b4fbe16bce3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_332767bf-4b7f-47c6-bfcb-ea404c460def" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_579b4f71-84be-48ca-9d1d-5b4fbe16bce3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_332767bf-4b7f-47c6-bfcb-ea404c460def" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_20a26e17-db8e-41c4-bc9b-3d45d23acbe6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_332767bf-4b7f-47c6-bfcb-ea404c460def" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_20a26e17-db8e-41c4-bc9b-3d45d23acbe6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_5d4a6e98-2d49-4ca8-a852-47661326bb1d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_332767bf-4b7f-47c6-bfcb-ea404c460def" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_5d4a6e98-2d49-4ca8-a852-47661326bb1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_ded0dd32-ed48-4116-b175-22973ed054cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_332767bf-4b7f-47c6-bfcb-ea404c460def" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_ded0dd32-ed48-4116-b175-22973ed054cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_5492a442-86a8-4efa-937d-0f1790525149" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_88ddb5b5-aff3-44eb-ab14-5e7cb675ea1b" xlink:to="loc_us-gaap_FinancialInstrumentAxis_5492a442-86a8-4efa-937d-0f1790525149" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5492a442-86a8-4efa-937d-0f1790525149_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5492a442-86a8-4efa-937d-0f1790525149" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_5492a442-86a8-4efa-937d-0f1790525149_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1c712699-8e9c-48cc-b0fb-6b1880c7ccf8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_5492a442-86a8-4efa-937d-0f1790525149" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1c712699-8e9c-48cc-b0fb-6b1880c7ccf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_033ae54f-00e5-40ef-9ec8-99f0077a265b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1c712699-8e9c-48cc-b0fb-6b1880c7ccf8" xlink:to="loc_us-gaap_CommercialPaperMember_033ae54f-00e5-40ef-9ec8-99f0077a265b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_3b9db988-5b38-415a-8d46-b7a4e31a4400" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_1c712699-8e9c-48cc-b0fb-6b1880c7ccf8" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_3b9db988-5b38-415a-8d46-b7a4e31a4400" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_1adf3d42-7a7d-47f7-84d7-c500b1b7897b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d7228f47-45a2-48a9-ab3c-2a424e4a18e4" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_1adf3d42-7a7d-47f7-84d7-c500b1b7897b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_a94fe491-4fb1-44c6-b7aa-0e6bcea0a51a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_1adf3d42-7a7d-47f7-84d7-c500b1b7897b" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_a94fe491-4fb1-44c6-b7aa-0e6bcea0a51a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_f22d9d99-9ac0-44c8-8f0f-4c0aa1afe63e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_1adf3d42-7a7d-47f7-84d7-c500b1b7897b" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterest_f22d9d99-9ac0-44c8-8f0f-4c0aa1afe63e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_561f0e33-8cb4-47eb-b985-7b986ba82323" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_1adf3d42-7a7d-47f7-84d7-c500b1b7897b" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_561f0e33-8cb4-47eb-b985-7b986ba82323" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract_32999d6d-616d-4565-b82f-1f71c8e94a34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_d7228f47-45a2-48a9-ab3c-2a424e4a18e4" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract_32999d6d-616d-4565-b82f-1f71c8e94a34" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightFairValueDisclosure_82ae067c-7b76-4274-9901-cb6488b8c989" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract_32999d6d-616d-4565-b82f-1f71c8e94a34" xlink:to="loc_oust_ClassOfWarrantOrRightFairValueDisclosure_82ae067c-7b76-4274-9901-cb6488b8c989" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_00223985-a033-48b0-9749-a11586b8cf7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FinancialLiabilitiesFairValueDisclosureAbstract_32999d6d-616d-4565-b82f-1f71c8e94a34" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_00223985-a033-48b0-9749-a11586b8cf7d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BalanceSheetComponentsScheduleofCashandCashEquivalentsDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BalanceSheetComponentsScheduleofCashandCashEquivalentsDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BalanceSheetComponentsScheduleofCashandCashEquivalentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsLineItems_80f713ae-92b2-47b9-bad5-fd2559a8a8cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_5543b80b-51f9-4c32-ae4d-25412c6583e8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfCashAndCashEquivalentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_80f713ae-92b2-47b9-bad5-fd2559a8a8cf" xlink:to="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_5543b80b-51f9-4c32-ae4d-25412c6583e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_b7297687-5013-4077-84ed-818d0e567289" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCashAndCashEquivalentsTable_5543b80b-51f9-4c32-ae4d-25412c6583e8" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_b7297687-5013-4077-84ed-818d0e567289" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_b7297687-5013-4077-84ed-818d0e567289_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_b7297687-5013-4077-84ed-818d0e567289" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_b7297687-5013-4077-84ed-818d0e567289_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_aafd47a8-e4f4-4b2a-a3db-d69cc96102e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_b7297687-5013-4077-84ed-818d0e567289" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_aafd47a8-e4f4-4b2a-a3db-d69cc96102e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_8d067c17-8392-4d81-b736-897dfd33b569" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_aafd47a8-e4f4-4b2a-a3db-d69cc96102e5" xlink:to="loc_us-gaap_MoneyMarketFundsMember_8d067c17-8392-4d81-b736-897dfd33b569" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialPaperMember_9a67cdd8-68ad-43c3-9a96-c6f588388bed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommercialPaperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_aafd47a8-e4f4-4b2a-a3db-d69cc96102e5" xlink:to="loc_us-gaap_CommercialPaperMember_9a67cdd8-68ad-43c3-9a96-c6f588388bed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Cash_3f93f273-881e-40b9-bf4d-8c68d75163da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Cash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_80f713ae-92b2-47b9-bad5-fd2559a8a8cf" xlink:to="loc_us-gaap_Cash_3f93f273-881e-40b9-bf4d-8c68d75163da" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_f7c44452-0a36-4b97-b502-d4ba3ac23000" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_80f713ae-92b2-47b9-bad5-fd2559a8a8cf" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_f7c44452-0a36-4b97-b502-d4ba3ac23000" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_abe8ac0b-a49c-4bb6-aafc-08bb234147ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CashAndCashEquivalentsLineItems_80f713ae-92b2-47b9-bad5-fd2559a8a8cf" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_abe8ac0b-a49c-4bb6-aafc-08bb234147ad" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BalanceSheetComponentsNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BalanceSheetComponentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BalanceSheetComponentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_90de4edc-9149-4893-af93-de205468f152" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_90de4edc-9149-4893-af93-de205468f152" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_90de4edc-9149-4893-af93-de205468f152_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_90de4edc-9149-4893-af93-de205468f152" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_90de4edc-9149-4893-af93-de205468f152_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_b5212e5f-471a-477d-aa62-41b755d029f9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_90de4edc-9149-4893-af93-de205468f152" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_b5212e5f-471a-477d-aa62-41b755d029f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CostOfRevenueMember_34a1d4b1-a87f-403a-b477-64079644a8a8" xlink:href="oust-20241231.xsd#oust_CostOfRevenueMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_b5212e5f-471a-477d-aa62-41b755d029f9" xlink:to="loc_oust_CostOfRevenueMember_34a1d4b1-a87f-403a-b477-64079644a8a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f0a10c28-a3ce-47b2-8d68-47742dd2f091" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_a3b76dfe-7c1f-4b91-a9f0-4eda59633f3d" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f0a10c28-a3ce-47b2-8d68-47742dd2f091" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_0a1091e3-287d-4d93-a79d-67d533162ab5" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_f0a10c28-a3ce-47b2-8d68-47742dd2f091" xlink:to="loc_oust_VelodyneLidarIncMember_0a1091e3-287d-4d93-a79d-67d533162ab5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_6a19c062-e512-485d-8cdb-a142325cf67a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_6a19c062-e512-485d-8cdb-a142325cf67a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_6a19c062-e512-485d-8cdb-a142325cf67a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_6a19c062-e512-485d-8cdb-a142325cf67a" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_6a19c062-e512-485d-8cdb-a142325cf67a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_a0369e05-25d1-40a8-8196-b2b8ab2b6dff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_6a19c062-e512-485d-8cdb-a142325cf67a" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_a0369e05-25d1-40a8-8196-b2b8ab2b6dff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AmazonWarrantMember_1cfd8e0b-b03a-47a8-8b86-0d3963ea366c" xlink:href="oust-20241231.xsd#oust_AmazonWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_a0369e05-25d1-40a8-8196-b2b8ab2b6dff" xlink:to="loc_oust_AmazonWarrantMember_1cfd8e0b-b03a-47a8-8b86-0d3963ea366c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_38d38552-36cf-4889-8730-028acb0f987b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_517faf7b-e3c6-45cc-bb52-502bf3204c5d" xlink:to="loc_srt_LitigationCaseAxis_38d38552-36cf-4889-8730-028acb0f987b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_38d38552-36cf-4889-8730-028acb0f987b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_38d38552-36cf-4889-8730-028acb0f987b" xlink:to="loc_srt_LitigationCaseTypeDomain_38d38552-36cf-4889-8730-028acb0f987b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_0391db6a-f258-4cdf-943e-8f87a2402057" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_38d38552-36cf-4889-8730-028acb0f987b" xlink:to="loc_srt_LitigationCaseTypeDomain_0391db6a-f258-4cdf-943e-8f87a2402057" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MoradpourV.VelodyneLidarInc.EtAl.Member_8c28981f-be77-422c-8ddc-7a053f3339de" xlink:href="oust-20241231.xsd#oust_MoradpourV.VelodyneLidarInc.EtAl.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_0391db6a-f258-4cdf-943e-8f87a2402057" xlink:to="loc_oust_MoradpourV.VelodyneLidarInc.EtAl.Member_8c28981f-be77-422c-8ddc-7a053f3339de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_d5dcd6d2-7f77-4a7f-8fdb-c89dcbabcdbc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_ShortTermInvestments_d5dcd6d2-7f77-4a7f-8fdb-c89dcbabcdbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryWriteDown_a030ed0b-41d9-46d2-a12d-7d2d99a1fc31" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InventoryWriteDown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_InventoryWriteDown_a030ed0b-41d9-46d2-a12d-7d2d99a1fc31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceSettlementsReceivableCurrent_bd119e10-b6f2-4056-93e0-dfcc69003035" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InsuranceSettlementsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_InsuranceSettlementsReceivableCurrent_bd119e10-b6f2-4056-93e0-dfcc69003035" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_c4040293-ff6d-440c-bbd1-936793805b34" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_Depreciation_c4040293-ff6d-440c-bbd1-936793805b34" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_e7c70a0a-ca76-4bf1-a170-0adf4a4dedac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_e7c70a0a-ca76-4bf1-a170-0adf4a4dedac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_fd3920c8-22ed-4a2f-a6bd-67a072243649" xlink:href="oust-20241231.xsd#oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_fd3920c8-22ed-4a2f-a6bd-67a072243649" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_fed9d926-71bd-49ca-8cd7-d6dd68b3d7e6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_fed9d926-71bd-49ca-8cd7-d6dd68b3d7e6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_03a31f00-5717-4aa1-8eca-88c774a46828" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_Goodwill_03a31f00-5717-4aa1-8eca-88c774a46828" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_d2c10f3a-2bda-4f4a-b459-e4c794d9cabc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_b6bb12ad-ba81-4717-8fdc-ca15d9609c4f" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_d2c10f3a-2bda-4f4a-b459-e4c794d9cabc" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BalanceSheetComponentsScheduleofPropertyandEquipmentDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BalanceSheetComponentsScheduleofPropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BalanceSheetComponentsScheduleofPropertyandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5f9424c5-c533-4352-9354-37f24272c1c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5f9424c5-c533-4352-9354-37f24272c1c8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_97dd9ace-27ee-48aa-b91b-bcaad590f702" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_5f9424c5-c533-4352-9354-37f24272c1c8" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_97dd9ace-27ee-48aa-b91b-bcaad590f702" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_97dd9ace-27ee-48aa-b91b-bcaad590f702_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_97dd9ace-27ee-48aa-b91b-bcaad590f702" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_97dd9ace-27ee-48aa-b91b-bcaad590f702_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_97dd9ace-27ee-48aa-b91b-bcaad590f702" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_7dfa2deb-9545-41f2-ab4d-5a0c8f7b5188" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_7dfa2deb-9545-41f2-ab4d-5a0c8f7b5188" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_b77abb96-874c-4520-858f-dd784f7550ca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_ComputerEquipmentMember_b77abb96-874c-4520-858f-dd784f7550ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VehiclesMember_fe429f67-2a6d-4604-b6b9-3e6258978577" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VehiclesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_VehiclesMember_fe429f67-2a6d-4604-b6b9-3e6258978577" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_c420ff1b-80c9-4dde-b922-14dc83e6f7be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_c420ff1b-80c9-4dde-b922-14dc83e6f7be" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_54fd9211-54b0-4678-96b6-1c9187e2f213" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_54fd9211-54b0-4678-96b6-1c9187e2f213" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_b9ecaf1f-13c5-4fe5-b349-9a0f8c60e85b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_ConstructionInProgressMember_b9ecaf1f-13c5-4fe5-b349-9a0f8c60e85b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_6dbe2e65-c560-47f2-ad91-08dc1be77d49" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_24ceb202-6773-4d35-ba74-677bcfc27bf8" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_6dbe2e65-c560-47f2-ad91-08dc1be77d49" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_aeb1421f-3634-490f-b0c5-4d2a8b43eb17" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_aeb1421f-3634-490f-b0c5-4d2a8b43eb17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_cdae13f0-41bb-4252-8d5b-8adb61cbd42b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_cdae13f0-41bb-4252-8d5b-8adb61cbd42b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_f9ce0925-db3b-4eba-9239-34c5c5da8a5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_f9ce0925-db3b-4eba-9239-34c5c5da8a5f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_e1f2152e-882c-4256-b7f8-e19a38575c95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_6e38dbed-65df-42ee-a86e-ec772bc64646" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_e1f2152e-882c-4256-b7f8-e19a38575c95" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BalanceSheetComponentsScheduleofPropertyandEquipmentbyGeographicLocationsDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BalanceSheetComponentsScheduleofPropertyandEquipmentbyGeographicLocationsDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BalanceSheetComponentsScheduleofPropertyandEquipmentbyGeographicLocationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9c455841-a6d6-4928-8d46-73df628ec210" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3286c8bb-10a0-4b59-aac4-189aff014d37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9c455841-a6d6-4928-8d46-73df628ec210" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3286c8bb-10a0-4b59-aac4-189aff014d37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_731a4063-c675-4fd0-bba1-7f8d6c176432" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_3286c8bb-10a0-4b59-aac4-189aff014d37" xlink:to="loc_srt_StatementGeographicalAxis_731a4063-c675-4fd0-bba1-7f8d6c176432" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_731a4063-c675-4fd0-bba1-7f8d6c176432_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_731a4063-c675-4fd0-bba1-7f8d6c176432" xlink:to="loc_srt_SegmentGeographicalDomain_731a4063-c675-4fd0-bba1-7f8d6c176432_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_731a4063-c675-4fd0-bba1-7f8d6c176432" xlink:to="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_6d114b03-f0a2-4237-b59c-699618812d88" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:to="loc_country_US_6d114b03-f0a2-4237-b59c-699618812d88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_TH_dafa9be0-bd31-482f-b669-3ea37783c12c" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_TH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:to="loc_country_TH_dafa9be0-bd31-482f-b669-3ea37783c12c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_FR_e1e98252-e2ae-4d93-bd63-be70417c9be8" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_FR"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:to="loc_country_FR_e1e98252-e2ae-4d93-bd63-be70417c9be8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_TW_c06f67ad-8c9f-4d09-a9a5-f9c314e529ed" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_TW"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:to="loc_country_TW_c06f67ad-8c9f-4d09-a9a5-f9c314e529ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OtherLocationsMember_32b0aa88-30e5-40cb-8f92-caa57b78501e" xlink:href="oust-20241231.xsd#oust_OtherLocationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0ede88b6-f571-453d-ae91-2d4654855fe9" xlink:to="loc_oust_OtherLocationsMember_32b0aa88-30e5-40cb-8f92-caa57b78501e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_450d0e3a-8913-4214-8f95-96b01f9c1e71" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_9c455841-a6d6-4928-8d46-73df628ec210" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_450d0e3a-8913-4214-8f95-96b01f9c1e71" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/BalanceSheetComponentsScheduleofAcquiredIntangibleAssetsDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#BalanceSheetComponentsScheduleofAcquiredIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/BalanceSheetComponentsScheduleofAcquiredIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f10137d5-5f75-4e9d-86e2-df02a63c6a30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f10137d5-5f75-4e9d-86e2-df02a63c6a30" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_65930516-a15e-4c48-9863-6942a0515f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f10137d5-5f75-4e9d-86e2-df02a63c6a30" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_65930516-a15e-4c48-9863-6942a0515f2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_65930516-a15e-4c48-9863-6942a0515f2a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_65930516-a15e-4c48-9863-6942a0515f2a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_65930516-a15e-4c48-9863-6942a0515f2a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_98dbf6c8-356e-4a0c-9c29-6d2c946c05dd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_65930516-a15e-4c48-9863-6942a0515f2a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_98dbf6c8-356e-4a0c-9c29-6d2c946c05dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_7c1813ff-3060-4b49-9ce6-e7ca3b947a9a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_98dbf6c8-356e-4a0c-9c29-6d2c946c05dd" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_7c1813ff-3060-4b49-9ce6-e7ca3b947a9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VendorRelationshipMember_c0669f4b-3ea2-4408-a0d9-479cce39c42f" xlink:href="oust-20241231.xsd#oust_VendorRelationshipMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_98dbf6c8-356e-4a0c-9c29-6d2c946c05dd" xlink:to="loc_oust_VendorRelationshipMember_c0669f4b-3ea2-4408-a0d9-479cce39c42f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_511ce6fa-a603-4cc7-b248-0f4d4aeb3d15" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_98dbf6c8-356e-4a0c-9c29-6d2c946c05dd" xlink:to="loc_us-gaap_CustomerRelationshipsMember_511ce6fa-a603-4cc7-b248-0f4d4aeb3d15" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_feae5aa1-0b15-46e6-853b-54fb6a05a30d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f10137d5-5f75-4e9d-86e2-df02a63c6a30" xlink:to="loc_srt_RangeAxis_feae5aa1-0b15-46e6-853b-54fb6a05a30d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_feae5aa1-0b15-46e6-853b-54fb6a05a30d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_feae5aa1-0b15-46e6-853b-54fb6a05a30d" xlink:to="loc_srt_RangeMember_feae5aa1-0b15-46e6-853b-54fb6a05a30d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7c74c0ca-12de-44ff-b1b8-b8a2b2020b1c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_feae5aa1-0b15-46e6-853b-54fb6a05a30d" xlink:to="loc_srt_RangeMember_7c74c0ca-12de-44ff-b1b8-b8a2b2020b1c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_4d2eca8a-a53a-4b6e-b428-b915c85bdb8f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7c74c0ca-12de-44ff-b1b8-b8a2b2020b1c" xlink:to="loc_srt_MinimumMember_4d2eca8a-a53a-4b6e-b428-b915c85bdb8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e6aea854-aa87-4921-9baf-fc821f94d66a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7c74c0ca-12de-44ff-b1b8-b8a2b2020b1c" xlink:to="loc_srt_MaximumMember_e6aea854-aa87-4921-9baf-fc821f94d66a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_91795340-72c9-491c-8d6a-54ebe5325d21" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_91795340-72c9-491c-8d6a-54ebe5325d21" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_447b6c79-2869-49c5-9644-069b1737a6d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_447b6c79-2869-49c5-9644-069b1737a6d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_14beed3f-3fb1-4683-b1dd-c2d1a2f30c53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_14beed3f-3fb1-4683-b1dd-c2d1a2f30c53" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_68beada8-ba84-4ff2-85df-4cf618c07414" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0de09bf8-6762-4ee5-9afb-93ac586512b8" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_68beada8-ba84-4ff2-85df-4cf618c07414" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/DebtDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#DebtDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/DebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_60d45992-2b2f-4840-8d21-bd52926611b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_us-gaap_DebtInstrumentAxis_60d45992-2b2f-4840-8d21-bd52926611b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_60d45992-2b2f-4840-8d21-bd52926611b0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_60d45992-2b2f-4840-8d21-bd52926611b0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_60d45992-2b2f-4840-8d21-bd52926611b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_167ab8d0-8da4-42ae-b548-5df98ab1df68" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_60d45992-2b2f-4840-8d21-bd52926611b0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_167ab8d0-8da4-42ae-b548-5df98ab1df68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_LoanAgreementWithHerculesCapitalIncMember_3000c7ed-318d-41c2-98e0-0e474ac86895" xlink:href="oust-20241231.xsd#oust_LoanAgreementWithHerculesCapitalIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_167ab8d0-8da4-42ae-b548-5df98ab1df68" xlink:to="loc_oust_LoanAgreementWithHerculesCapitalIncMember_3000c7ed-318d-41c2-98e0-0e474ac86895" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CreditAgreementWithUBSBankUSAAndUBSFinancialServicesMember_851f3577-7d22-471c-b3d4-34c00f3cc7e3" xlink:href="oust-20241231.xsd#oust_CreditAgreementWithUBSBankUSAAndUBSFinancialServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_167ab8d0-8da4-42ae-b548-5df98ab1df68" xlink:to="loc_oust_CreditAgreementWithUBSBankUSAAndUBSFinancialServicesMember_851f3577-7d22-471c-b3d4-34c00f3cc7e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_UBSMember_629be400-8518-49ca-997d-57e25e8eb750" xlink:href="oust-20241231.xsd#oust_UBSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_167ab8d0-8da4-42ae-b548-5df98ab1df68" xlink:to="loc_oust_UBSMember_629be400-8518-49ca-997d-57e25e8eb750" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_39d022e2-21c7-4c25-84a4-753eface8d8e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_39d022e2-21c7-4c25-84a4-753eface8d8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_39d022e2-21c7-4c25-84a4-753eface8d8e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_39d022e2-21c7-4c25-84a4-753eface8d8e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_39d022e2-21c7-4c25-84a4-753eface8d8e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4d89d3e7-1020-4bc3-9b93-17751edbddbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_39d022e2-21c7-4c25-84a4-753eface8d8e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4d89d3e7-1020-4bc3-9b93-17751edbddbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_TermLoanMember_1946321a-c2f6-42b4-8e85-9bc068454035" xlink:href="oust-20241231.xsd#oust_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_4d89d3e7-1020-4bc3-9b93-17751edbddbd" xlink:to="loc_oust_TermLoanMember_1946321a-c2f6-42b4-8e85-9bc068454035" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_InterestRateScenarioAxis_2d483da1-dd36-448e-a3b7-cfdbc52e42b6" xlink:href="oust-20241231.xsd#oust_InterestRateScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_oust_InterestRateScenarioAxis_2d483da1-dd36-448e-a3b7-cfdbc52e42b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_InterestRateScenarioDomain_2d483da1-dd36-448e-a3b7-cfdbc52e42b6_default" xlink:href="oust-20241231.xsd#oust_InterestRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_oust_InterestRateScenarioAxis_2d483da1-dd36-448e-a3b7-cfdbc52e42b6" xlink:to="loc_oust_InterestRateScenarioDomain_2d483da1-dd36-448e-a3b7-cfdbc52e42b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_InterestRateScenarioDomain_8d4953b6-5d31-4229-8e08-d376ce02c5a6" xlink:href="oust-20241231.xsd#oust_InterestRateScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_oust_InterestRateScenarioAxis_2d483da1-dd36-448e-a3b7-cfdbc52e42b6" xlink:to="loc_oust_InterestRateScenarioDomain_8d4953b6-5d31-4229-8e08-d376ce02c5a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_InterestRateNotSubjectToFinancialCovenantMember_e66a421f-e462-4af8-a32a-02624ee9cd16" xlink:href="oust-20241231.xsd#oust_InterestRateNotSubjectToFinancialCovenantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oust_InterestRateScenarioDomain_8d4953b6-5d31-4229-8e08-d376ce02c5a6" xlink:to="loc_oust_InterestRateNotSubjectToFinancialCovenantMember_e66a421f-e462-4af8-a32a-02624ee9cd16" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_InterestRateSubjectToFinancialCovenantMember_08f76b71-94d1-434e-9b2e-eb8e9adf05c2" xlink:href="oust-20241231.xsd#oust_InterestRateSubjectToFinancialCovenantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oust_InterestRateScenarioDomain_8d4953b6-5d31-4229-8e08-d376ce02c5a6" xlink:to="loc_oust_InterestRateSubjectToFinancialCovenantMember_08f76b71-94d1-434e-9b2e-eb8e9adf05c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_ea6afff2-6e18-455b-b878-4d5206ffc400" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_us-gaap_VariableRateAxis_ea6afff2-6e18-455b-b878-4d5206ffc400" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_ea6afff2-6e18-455b-b878-4d5206ffc400_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_ea6afff2-6e18-455b-b878-4d5206ffc400" xlink:to="loc_us-gaap_VariableRateDomain_ea6afff2-6e18-455b-b878-4d5206ffc400_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_57bc04ed-e388-45a3-860e-2555b5b08790" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_ea6afff2-6e18-455b-b878-4d5206ffc400" xlink:to="loc_us-gaap_VariableRateDomain_57bc04ed-e388-45a3-860e-2555b5b08790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrimeRateMember_b4b7eb53-1176-4965-bd50-bbb9d92097c0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PrimeRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_57bc04ed-e388-45a3-860e-2555b5b08790" xlink:to="loc_us-gaap_PrimeRateMember_b4b7eb53-1176-4965-bd50-bbb9d92097c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_2756a055-8d6f-49dc-a932-fb733fad000f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_57bc04ed-e388-45a3-860e-2555b5b08790" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrMember_2756a055-8d6f-49dc-a932-fb733fad000f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_61142ca8-c0a5-4072-aaae-dc7b17e8250c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_srt_RangeAxis_61142ca8-c0a5-4072-aaae-dc7b17e8250c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_61142ca8-c0a5-4072-aaae-dc7b17e8250c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_61142ca8-c0a5-4072-aaae-dc7b17e8250c" xlink:to="loc_srt_RangeMember_61142ca8-c0a5-4072-aaae-dc7b17e8250c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6f578927-d5a6-48be-80c5-1ab5db52b7c5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_61142ca8-c0a5-4072-aaae-dc7b17e8250c" xlink:to="loc_srt_RangeMember_6f578927-d5a6-48be-80c5-1ab5db52b7c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b4db8858-6f60-476e-9a11-271c5f73c39a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6f578927-d5a6-48be-80c5-1ab5db52b7c5" xlink:to="loc_srt_MinimumMember_b4db8858-6f60-476e-9a11-271c5f73c39a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_938588f3-2caf-4968-8f99-28af517ae338" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_6f578927-d5a6-48be-80c5-1ab5db52b7c5" xlink:to="loc_srt_MaximumMember_938588f3-2caf-4968-8f99-28af517ae338" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_a99c1352-d6b9-439e-ad2b-7aaf727bcd62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_us-gaap_CreditFacilityAxis_a99c1352-d6b9-439e-ad2b-7aaf727bcd62" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a99c1352-d6b9-439e-ad2b-7aaf727bcd62_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_a99c1352-d6b9-439e-ad2b-7aaf727bcd62" xlink:to="loc_us-gaap_CreditFacilityDomain_a99c1352-d6b9-439e-ad2b-7aaf727bcd62_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ac31f630-24d1-4b05-ad9c-1ad48f7a6994" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_a99c1352-d6b9-439e-ad2b-7aaf727bcd62" xlink:to="loc_us-gaap_CreditFacilityDomain_ac31f630-24d1-4b05-ad9c-1ad48f7a6994" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_c0dfde4e-8447-49da-867a-4f158b97c9be" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_ac31f630-24d1-4b05-ad9c-1ad48f7a6994" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_c0dfde4e-8447-49da-867a-4f158b97c9be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_f07974b4-c3e6-4fcb-af04-38f13f9a6275" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_0c32d1f4-d052-4013-8cfd-69e14eb43bb0" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_f07974b4-c3e6-4fcb-af04-38f13f9a6275" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f07974b4-c3e6-4fcb-af04-38f13f9a6275_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_f07974b4-c3e6-4fcb-af04-38f13f9a6275" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f07974b4-c3e6-4fcb-af04-38f13f9a6275_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_dff057c5-3c5c-426e-a244-80ba0ed7df19" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsAxis_f07974b4-c3e6-4fcb-af04-38f13f9a6275" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_dff057c5-3c5c-426e-a244-80ba0ed7df19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MinimumLiquidityPursuantToCreditAgreementMember_86e50116-f993-4ccc-b06d-2fd23fd65f2b" xlink:href="oust-20241231.xsd#oust_MinimumLiquidityPursuantToCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_dff057c5-3c5c-426e-a244-80ba0ed7df19" xlink:to="loc_oust_MinimumLiquidityPursuantToCreditAgreementMember_86e50116-f993-4ccc-b06d-2fd23fd65f2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3ae789c4-5334-465c-94bf-1fe27cecc49a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_3ae789c4-5334-465c-94bf-1fe27cecc49a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_2187982f-e3aa-469d-8b4b-f3905356c2f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_2187982f-e3aa-469d-8b4b-f3905356c2f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_a0c8941e-f121-4d30-a5a4-a6a2b270bd56" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_a0c8941e-f121-4d30-a5a4-a6a2b270bd56" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_DebtInstrumentCovenantTermsCashInDepositAccountsMinimumAmount_fb723bc6-1f41-4709-9671-eb8423fb9410" xlink:href="oust-20241231.xsd#oust_DebtInstrumentCovenantTermsCashInDepositAccountsMinimumAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_oust_DebtInstrumentCovenantTermsCashInDepositAccountsMinimumAmount_fb723bc6-1f41-4709-9671-eb8423fb9410" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f1d14e63-ce51-49ed-8496-475ed49571d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_f1d14e63-ce51-49ed-8496-475ed49571d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_3cd7b86f-9554-4bed-8256-8bd2f062e841" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_3cd7b86f-9554-4bed-8256-8bd2f062e841" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PaymentsForCashFacilityAndLegalFees_43ca4b11-aa78-4321-ac79-7a5e05afb077" xlink:href="oust-20241231.xsd#oust_PaymentsForCashFacilityAndLegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_oust_PaymentsForCashFacilityAndLegalFees_43ca4b11-aa78-4321-ac79-7a5e05afb077" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNet_0e9c696f-8c03-496c-9eef-60bdd21dd07c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredFinanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DeferredFinanceCostsNet_0e9c696f-8c03-496c-9eef-60bdd21dd07c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_1fb8d456-3063-4cb5-80ad-b02f6f2deb76" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_1fb8d456-3063-4cb5-80ad-b02f6f2deb76" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_472f7478-c2e3-4ec9-8029-88feb2810a4b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_472f7478-c2e3-4ec9-8029-88feb2810a4b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCash_0b8f3f66-49df-4f14-923f-8a21ffd0474a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_RestrictedCash_0b8f3f66-49df-4f14-923f-8a21ffd0474a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_DebtInstrumentVariableInterestRateMargin_5ea332d8-2f1c-42e7-98cf-377e406dcb02" xlink:href="oust-20241231.xsd#oust_DebtInstrumentVariableInterestRateMargin"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_oust_DebtInstrumentVariableInterestRateMargin_5ea332d8-2f1c-42e7-98cf-377e406dcb02" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_DebtInstrumentLiquidityPremiumPercentage_54cc91c4-9d66-4726-a477-8ef54541b888" xlink:href="oust-20241231.xsd#oust_DebtInstrumentLiquidityPremiumPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_oust_DebtInstrumentLiquidityPremiumPercentage_54cc91c4-9d66-4726-a477-8ef54541b888" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_2da86c45-f4e6-40b5-bbe1-d218fee7e8b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_0bc901b2-b7b3-4686-aa08-2ffa7b33819f" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_2da86c45-f4e6-40b5-bbe1-d218fee7e8b9" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/WarrantsNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#WarrantsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/WarrantsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_099c0bc9-6996-4f98-93d7-cf225b08443c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_srt_CounterpartyNameAxis_099c0bc9-6996-4f98-93d7-cf225b08443c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_099c0bc9-6996-4f98-93d7-cf225b08443c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_099c0bc9-6996-4f98-93d7-cf225b08443c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_099c0bc9-6996-4f98-93d7-cf225b08443c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3ec343b0-8354-4b17-93ab-2b5879de16dd" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_099c0bc9-6996-4f98-93d7-cf225b08443c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3ec343b0-8354-4b17-93ab-2b5879de16dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SponsorMember_9cd3c9a7-daf9-45e4-b1da-9f7e719745c9" xlink:href="oust-20241231.xsd#oust_SponsorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3ec343b0-8354-4b17-93ab-2b5879de16dd" xlink:to="loc_oust_SponsorMember_9cd3c9a7-daf9-45e4-b1da-9f7e719745c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_Amazon.comNVInvestmentHoldingsLLLCMember_b61aa3fe-6888-43de-beb4-0f7e88c7d5a0" xlink:href="oust-20241231.xsd#oust_Amazon.comNVInvestmentHoldingsLLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_3ec343b0-8354-4b17-93ab-2b5879de16dd" xlink:to="loc_oust_Amazon.comNVInvestmentHoldingsLLLCMember_b61aa3fe-6888-43de-beb4-0f7e88c7d5a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_ec76d552-f2bb-42af-9fb1-6c207a659649" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_ec76d552-f2bb-42af-9fb1-6c207a659649" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_ec76d552-f2bb-42af-9fb1-6c207a659649_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_ec76d552-f2bb-42af-9fb1-6c207a659649" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_ec76d552-f2bb-42af-9fb1-6c207a659649_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_ec76d552-f2bb-42af-9fb1-6c207a659649" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PrivatePlacementWarrantsMember_d8842d7f-bb63-43cd-b52f-1b1ad7db72f8" xlink:href="oust-20241231.xsd#oust_PrivatePlacementWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:to="loc_oust_PrivatePlacementWarrantsMember_d8842d7f-bb63-43cd-b52f-1b1ad7db72f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PublicWarrantsMember_ba767163-c149-441f-9096-b2c5693c5394" xlink:href="oust-20241231.xsd#oust_PublicWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:to="loc_oust_PublicWarrantsMember_ba767163-c149-441f-9096-b2c5693c5394" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AmazonWarrantMember_3c68bba1-ddfd-4c4a-b9df-f5c990b4c937" xlink:href="oust-20241231.xsd#oust_AmazonWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:to="loc_oust_AmazonWarrantMember_3c68bba1-ddfd-4c4a-b9df-f5c990b4c937" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AmazonWarrantCommonStockVestedMember_01efce98-8c1e-42e0-a00b-3faaa389b2b8" xlink:href="oust-20241231.xsd#oust_AmazonWarrantCommonStockVestedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:to="loc_oust_AmazonWarrantCommonStockVestedMember_01efce98-8c1e-42e0-a00b-3faaa389b2b8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AmazonWarrantCommonStockUnvestedMember_0100fdce-5717-4fb2-b91a-5ae5f2e5d115" xlink:href="oust-20241231.xsd#oust_AmazonWarrantCommonStockUnvestedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_78ce9417-8ceb-4877-9a4c-f86ce6b54d4e" xlink:to="loc_oust_AmazonWarrantCommonStockUnvestedMember_0100fdce-5717-4fb2-b91a-5ae5f2e5d115" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_dei_LegalEntityAxis_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90_default" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90" xlink:to="loc_dei_EntityDomain_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_d4b5aec8-81f6-4f27-8bb5-abf28cf37d6b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_7fde86b4-0dc4-4f5d-bfd2-4bc013d8ea90" xlink:to="loc_dei_EntityDomain_d4b5aec8-81f6-4f27-8bb5-abf28cf37d6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SponsorMember_2cd71791-8c37-4e0a-a66e-f2d92841cf7a" xlink:href="oust-20241231.xsd#oust_SponsorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_d4b5aec8-81f6-4f27-8bb5-abf28cf37d6b" xlink:to="loc_oust_SponsorMember_2cd71791-8c37-4e0a-a66e-f2d92841cf7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ColonnadeAcquisitionCorpMember_bc820a68-33e6-4a54-bb04-5dcbb98e0b30" xlink:href="oust-20241231.xsd#oust_ColonnadeAcquisitionCorpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_d4b5aec8-81f6-4f27-8bb5-abf28cf37d6b" xlink:to="loc_oust_ColonnadeAcquisitionCorpMember_bc820a68-33e6-4a54-bb04-5dcbb98e0b30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2e40c4e8-c7f8-4087-b535-48b6b0728179" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConversionOfStockByUniqueDescriptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2e40c4e8-c7f8-4087-b535-48b6b0728179" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockNameDomain_2e40c4e8-c7f8-4087-b535-48b6b0728179_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConversionOfStockNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2e40c4e8-c7f8-4087-b535-48b6b0728179" xlink:to="loc_us-gaap_ConversionOfStockNameDomain_2e40c4e8-c7f8-4087-b535-48b6b0728179_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockNameDomain_647ac1ea-0c86-449d-a37f-cf84990c3eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConversionOfStockNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConversionOfStockByUniqueDescriptionAxis_2e40c4e8-c7f8-4087-b535-48b6b0728179" xlink:to="loc_us-gaap_ConversionOfStockNameDomain_647ac1ea-0c86-449d-a37f-cf84990c3eb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ConversionOfCLAUnitsToOusterCommonStockMember_19b990b2-ef67-43cd-bf76-b4856811a769" xlink:href="oust-20241231.xsd#oust_ConversionOfCLAUnitsToOusterCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockNameDomain_647ac1ea-0c86-449d-a37f-cf84990c3eb5" xlink:to="loc_oust_ConversionOfCLAUnitsToOusterCommonStockMember_19b990b2-ef67-43cd-bf76-b4856811a769" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ConversionOfWarrantToOusterCommonStockMember_1b1d2e0e-1947-423f-9fa6-b1f8fe98ee41" xlink:href="oust-20241231.xsd#oust_ConversionOfWarrantToOusterCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockNameDomain_647ac1ea-0c86-449d-a37f-cf84990c3eb5" xlink:to="loc_oust_ConversionOfWarrantToOusterCommonStockMember_1b1d2e0e-1947-423f-9fa6-b1f8fe98ee41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ConversionOfCLAUnitsToPublicWarrantMember_7fce9380-35d4-42dc-a0fa-f7351387f5dc" xlink:href="oust-20241231.xsd#oust_ConversionOfCLAUnitsToPublicWarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConversionOfStockNameDomain_647ac1ea-0c86-449d-a37f-cf84990c3eb5" xlink:to="loc_oust_ConversionOfCLAUnitsToPublicWarrantMember_7fce9380-35d4-42dc-a0fa-f7351387f5dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_22505975-fc9a-423b-a927-137b9ce6bc05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_22505975-fc9a-423b-a927-137b9ce6bc05" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_22505975-fc9a-423b-a927-137b9ce6bc05_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_22505975-fc9a-423b-a927-137b9ce6bc05" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_22505975-fc9a-423b-a927-137b9ce6bc05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_df775d91-8c5c-4a08-a436-c8d68bf2684f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_22505975-fc9a-423b-a927-137b9ce6bc05" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_df775d91-8c5c-4a08-a436-c8d68bf2684f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_39e39373-0a80-43b1-9517-4aef40379a47" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_df775d91-8c5c-4a08-a436-c8d68bf2684f" xlink:to="loc_oust_VelodyneLidarIncMember_39e39373-0a80-43b1-9517-4aef40379a47" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_a47ac163-a160-447d-8072-5a471492eba0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_a47ac163-a160-447d-8072-5a471492eba0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_a47ac163-a160-447d-8072-5a471492eba0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_a47ac163-a160-447d-8072-5a471492eba0" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_a47ac163-a160-447d-8072-5a471492eba0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_a47ac163-a160-447d-8072-5a471492eba0" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExpectedTermMember_9a588d56-bef1-434f-b1b1-6ddb49196c7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputExpectedTermMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:to="loc_us-gaap_MeasurementInputExpectedTermMember_9a588d56-bef1-434f-b1b1-6ddb49196c7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPriceVolatilityMember_1e1b4f8a-cfa0-4050-b4a2-efc8c02d3a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputPriceVolatilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:to="loc_us-gaap_MeasurementInputPriceVolatilityMember_1e1b4f8a-cfa0-4050-b4a2-efc8c02d3a0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_5832b2e0-62b0-425b-bb18-07163503336b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:to="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_5832b2e0-62b0-425b-bb18-07163503336b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExpectedDividendRateMember_1157f91b-f001-4eec-af89-b9cf975fd83a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputExpectedDividendRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_8fc3f7b6-e179-44c4-83ca-b480785fdd7d" xlink:to="loc_us-gaap_MeasurementInputExpectedDividendRateMember_1157f91b-f001-4eec-af89-b9cf975fd83a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_7ff16630-29dc-4e0a-a5a1-2420c4049e3b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_ValuationTechniqueAxis_7ff16630-29dc-4e0a-a5a1-2420c4049e3b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_7ff16630-29dc-4e0a-a5a1-2420c4049e3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_7ff16630-29dc-4e0a-a5a1-2420c4049e3b" xlink:to="loc_us-gaap_ValuationTechniqueDomain_7ff16630-29dc-4e0a-a5a1-2420c4049e3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_822be4d4-cc4a-4246-a243-b7a9ce774866" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_7ff16630-29dc-4e0a-a5a1-2420c4049e3b" xlink:to="loc_us-gaap_ValuationTechniqueDomain_822be4d4-cc4a-4246-a243-b7a9ce774866" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueOptionPricingModelMember_657be508-7a3e-438b-b17b-35e46c48756b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueOptionPricingModelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_822be4d4-cc4a-4246-a243-b7a9ce774866" xlink:to="loc_us-gaap_ValuationTechniqueOptionPricingModelMember_657be508-7a3e-438b-b17b-35e46c48756b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_60d24960-0bfe-4805-a0fc-ad3ae7402004" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_d429bd63-3646-450e-a752-b915528f74a6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_60d24960-0bfe-4805-a0fc-ad3ae7402004" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_60d24960-0bfe-4805-a0fc-ad3ae7402004_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_60d24960-0bfe-4805-a0fc-ad3ae7402004" xlink:to="loc_us-gaap_EquityComponentDomain_60d24960-0bfe-4805-a0fc-ad3ae7402004_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_5bf4ad91-e005-4c53-b7d2-875c07ec545e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_60d24960-0bfe-4805-a0fc-ad3ae7402004" xlink:to="loc_us-gaap_EquityComponentDomain_5bf4ad91-e005-4c53-b7d2-875c07ec545e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3939cc9a-46cb-49df-95d0-d8565579dca4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_5bf4ad91-e005-4c53-b7d2-875c07ec545e" xlink:to="loc_us-gaap_CommonStockMember_3939cc9a-46cb-49df-95d0-d8565579dca4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_219053fc-f5d5-43c5-a375-e4c47a41b978" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_219053fc-f5d5-43c5-a375-e4c47a41b978" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfWarrants_dbf29ca7-a366-42f9-86c5-68953e7de472" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfWarrants_dbf29ca7-a366-42f9-86c5-68953e7de472" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightExercisableThresholdPeriod_96e0f927-146e-43a5-82cb-eb70d2d59ef0" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightExercisableThresholdPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightExercisableThresholdPeriod_96e0f927-146e-43a5-82cb-eb70d2d59ef0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingTerm_c2fdd037-8929-4072-a402-92bfcdcff107" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WarrantsAndRightsOutstandingTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingTerm_c2fdd037-8929-4072-a402-92bfcdcff107" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_4e16e71d-9af7-41bb-8d1e-0c1fd998e2de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_4e16e71d-9af7-41bb-8d1e-0c1fd998e2de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstanding_439d7074-04f4-4df5-9fb7-c4045f7b1e86" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WarrantsAndRightsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_WarrantsAndRightsOutstanding_439d7074-04f4-4df5-9fb7-c4045f7b1e86" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_765cdf94-122a-40eb-8729-15db537c0014" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight_765cdf94-122a-40eb-8729-15db537c0014" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightConversionRatio_c286ce35-269a-42a0-b9b4-a68b4dea8392" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightConversionRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightConversionRatio_c286ce35-269a-42a0-b9b4-a68b4dea8392" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_RedemptionOfWarrantPricePerShare_80a6829a-388e-42a1-9ca8-ac2b845b8526" xlink:href="oust-20241231.xsd#oust_RedemptionOfWarrantPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_RedemptionOfWarrantPricePerShare_80a6829a-388e-42a1-9ca8-ac2b845b8526" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightExercisableThresholdCommonStockPriceForRedemption_7bacfd97-e788-4f46-8d71-a6d8ada7b4f8" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightExercisableThresholdCommonStockPriceForRedemption"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightExercisableThresholdCommonStockPriceForRedemption_7bacfd97-e788-4f46-8d71-a6d8ada7b4f8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightExercisableThresholdTradingDays_eed1ebaa-2bd7-4ba9-ac97-584087cee029" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightExercisableThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightExercisableThresholdTradingDays_eed1ebaa-2bd7-4ba9-ac97-584087cee029" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightExercisableThresholdTradingDayPeriod_00dc476d-5cd1-40bc-89f7-c096e89715cb" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightExercisableThresholdTradingDayPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightExercisableThresholdTradingDayPeriod_00dc476d-5cd1-40bc-89f7-c096e89715cb" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationConsiderationTransferredNumberOfWarrantsAcquired_f044c04b-a9fc-4634-8511-e0cf4f434167" xlink:href="oust-20241231.xsd#oust_BusinessCombinationConsiderationTransferredNumberOfWarrantsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_BusinessCombinationConsiderationTransferredNumberOfWarrantsAcquired_f044c04b-a9fc-4634-8511-e0cf4f434167" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_NumberOfBusinessDaysPriorToDateNoticeOfRedemptionSentToWarrantHolders_8efd4d77-0b01-4437-8cd8-5a9d7fe75d5e" xlink:href="oust-20241231.xsd#oust_NumberOfBusinessDaysPriorToDateNoticeOfRedemptionSentToWarrantHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_NumberOfBusinessDaysPriorToDateNoticeOfRedemptionSentToWarrantHolders_8efd4d77-0b01-4437-8cd8-5a9d7fe75d5e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_186a1f39-1f04-412c-b720-81ea47885894" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_186a1f39-1f04-412c-b720-81ea47885894" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightAdditionalNumberOfSecuritiesCalledByWarrantsOrRights_26951bce-e5cc-4222-856d-456d4ca3d81c" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightAdditionalNumberOfSecuritiesCalledByWarrantsOrRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightAdditionalNumberOfSecuritiesCalledByWarrantsOrRights_26951bce-e5cc-4222-856d-456d4ca3d81c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightVestingOfWarrantUponAcquisitionPercent_89725655-84d2-4b05-b671-301c1cd2eab4" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightVestingOfWarrantUponAcquisitionPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightVestingOfWarrantUponAcquisitionPercent_89725655-84d2-4b05-b671-301c1cd2eab4" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightVestedWarrantsNumberOfCommonSharesRepresented_eaaa702e-acc0-49b2-8002-287ca7e0974b" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightVestedWarrantsNumberOfCommonSharesRepresented"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightVestedWarrantsNumberOfCommonSharesRepresented_eaaa702e-acc0-49b2-8002-287ca7e0974b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_f313108c-97d5-410a-9f2c-9d5eb1c859d9" xlink:href="oust-20241231.xsd#oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_BusinessCombinationConsiderationTransferredWarrantsAndRightsAssumed_f313108c-97d5-410a-9f2c-9d5eb1c859d9" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightVestingBasisPaymentsByCounterpartyForGoodsAndServicesMaximum_ebf9665a-8b0a-4050-8791-24b6f795bb20" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightVestingBasisPaymentsByCounterpartyForGoodsAndServicesMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightVestingBasisPaymentsByCounterpartyForGoodsAndServicesMaximum_ebf9665a-8b0a-4050-8791-24b6f795bb20" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightUnvestedWarrantsNumberOfCommonSharesRepresented_30b4e4f8-6108-4157-96ab-e284af15365e" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightUnvestedWarrantsNumberOfCommonSharesRepresented"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightUnvestedWarrantsNumberOfCommonSharesRepresented_30b4e4f8-6108-4157-96ab-e284af15365e" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightNumberOfWarrantsVestedDuringPeriod_3d57d577-08ae-4c6a-a62c-b1e6a382f7b8" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightNumberOfWarrantsVestedDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightNumberOfWarrantsVestedDuringPeriod_3d57d577-08ae-4c6a-a62c-b1e6a382f7b8" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightWarrantVestedNoncashReductionToRevenue_67a63aec-3824-4c19-8a8d-d460fdfceb5a" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightWarrantVestedNoncashReductionToRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightWarrantVestedNoncashReductionToRevenue_67a63aec-3824-4c19-8a8d-d460fdfceb5a" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_608b6a02-368e-43e5-8b42-7458c636522c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WarrantsAndRightsOutstandingMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_608b6a02-368e-43e5-8b42-7458c636522c" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ClassOfWarrantOrRightNumberOfWarrantsVested_a727f9d9-0991-46a9-9e68-5e0662d3c6a5" xlink:href="oust-20241231.xsd#oust_ClassOfWarrantOrRightNumberOfWarrantsVested"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_be86ba0a-7e65-475d-aab2-37c36207e626" xlink:to="loc_oust_ClassOfWarrantOrRightNumberOfWarrantsVested_a727f9d9-0991-46a9-9e68-5e0662d3c6a5" xlink:type="arc" order="24"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/WarrantsScheduleofFairValueMeasurementInputsofPrivatePlacementWarrantsDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#WarrantsScheduleofFairValueMeasurementInputsofPrivatePlacementWarrantsDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/WarrantsScheduleofFairValueMeasurementInputsofPrivatePlacementWarrantsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightLineItems_8d73e514-14cf-4759-a2d4-aa1d5f20f527" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightTable_7a58780f-4eb4-4b3b-88a2-4ba1e7e855da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_8d73e514-14cf-4759-a2d4-aa1d5f20f527" xlink:to="loc_us-gaap_ClassOfWarrantOrRightTable_7a58780f-4eb4-4b3b-88a2-4ba1e7e855da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_2d259961-43b3-4935-ac74-f0548c2cd41c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_7a58780f-4eb4-4b3b-88a2-4ba1e7e855da" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_2d259961-43b3-4935-ac74-f0548c2cd41c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_2d259961-43b3-4935-ac74-f0548c2cd41c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_2d259961-43b3-4935-ac74-f0548c2cd41c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_2d259961-43b3-4935-ac74-f0548c2cd41c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_2d259961-43b3-4935-ac74-f0548c2cd41c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputSharePriceMember_c46ffee6-e302-458f-a33b-5f50f644eefd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputSharePriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:to="loc_us-gaap_MeasurementInputSharePriceMember_c46ffee6-e302-458f-a33b-5f50f644eefd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExercisePriceMember_5b957b01-f599-4bc2-87e4-2964b34df2cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputExercisePriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:to="loc_us-gaap_MeasurementInputExercisePriceMember_5b957b01-f599-4bc2-87e4-2964b34df2cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExpectedTermMember_2347d221-fa8e-4e37-99e9-4895dceeec74" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputExpectedTermMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:to="loc_us-gaap_MeasurementInputExpectedTermMember_2347d221-fa8e-4e37-99e9-4895dceeec74" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPriceVolatilityMember_b2363be6-45d9-45aa-a460-8a865eb1508d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputPriceVolatilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:to="loc_us-gaap_MeasurementInputPriceVolatilityMember_b2363be6-45d9-45aa-a460-8a865eb1508d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_f3bffa0f-de70-463c-8699-69ffa880d030" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_e13a8025-e1db-4871-9b66-ddeafb3209b4" xlink:to="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_f3bffa0f-de70-463c-8699-69ffa880d030" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_1fe3827f-3333-44b6-a26f-9aba3b257477" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_7a58780f-4eb4-4b3b-88a2-4ba1e7e855da" xlink:to="loc_us-gaap_ValuationTechniqueAxis_1fe3827f-3333-44b6-a26f-9aba3b257477" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_1fe3827f-3333-44b6-a26f-9aba3b257477_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_1fe3827f-3333-44b6-a26f-9aba3b257477" xlink:to="loc_us-gaap_ValuationTechniqueDomain_1fe3827f-3333-44b6-a26f-9aba3b257477_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_9cd971d1-12f1-4016-89fc-8f4c65ebd2dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_1fe3827f-3333-44b6-a26f-9aba3b257477" xlink:to="loc_us-gaap_ValuationTechniqueDomain_9cd971d1-12f1-4016-89fc-8f4c65ebd2dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueOptionPricingModelMember_4bbfd5da-5f02-4314-8607-e51e4d215abc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationTechniqueOptionPricingModelMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_9cd971d1-12f1-4016-89fc-8f4c65ebd2dc" xlink:to="loc_us-gaap_ValuationTechniqueOptionPricingModelMember_4bbfd5da-5f02-4314-8607-e51e4d215abc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_8995f8df-4b3d-4c3e-95d6-83f6250b0a05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_7a58780f-4eb4-4b3b-88a2-4ba1e7e855da" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_8995f8df-4b3d-4c3e-95d6-83f6250b0a05" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_8995f8df-4b3d-4c3e-95d6-83f6250b0a05_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_8995f8df-4b3d-4c3e-95d6-83f6250b0a05" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_8995f8df-4b3d-4c3e-95d6-83f6250b0a05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_aac92bad-8374-4bfa-8de6-916beb63bce7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_8995f8df-4b3d-4c3e-95d6-83f6250b0a05" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_aac92bad-8374-4bfa-8de6-916beb63bce7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PrivatePlacementWarrantsMember_707a7721-287f-4dbf-81fd-5475f8ba9049" xlink:href="oust-20241231.xsd#oust_PrivatePlacementWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_aac92bad-8374-4bfa-8de6-916beb63bce7" xlink:to="loc_oust_PrivatePlacementWarrantsMember_707a7721-287f-4dbf-81fd-5475f8ba9049" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_45d6cb2a-7ac4-4f32-ba35-05a4bbaf3e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WarrantsAndRightsOutstandingMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_8d73e514-14cf-4759-a2d4-aa1d5f20f527" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_45d6cb2a-7ac4-4f32-ba35-05a4bbaf3e2f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_e48d0aa9-2782-4d0f-93ce-1b0a709854b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_e48d0aa9-2782-4d0f-93ce-1b0a709854b9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e48d0aa9-2782-4d0f-93ce-1b0a709854b9" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_4ee00bd8-6dc9-4243-a8df-ca5b20013d0a" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_HeadquartersLocatedInSanFranciscoCaliforniaMember_0c33ef8c-d130-42f7-9f16-00e0c3784bcb" xlink:href="oust-20241231.xsd#oust_HeadquartersLocatedInSanFranciscoCaliforniaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_HeadquartersLocatedInSanFranciscoCaliforniaMember_0c33ef8c-d130-42f7-9f16-00e0c3784bcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OfficeSpaceAdjacentToCorporateHeadquartersMember_1d070cef-4dbb-4094-b333-52d1e0f06b5f" xlink:href="oust-20241231.xsd#oust_OfficeSpaceAdjacentToCorporateHeadquartersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_OfficeSpaceAdjacentToCorporateHeadquartersMember_1d070cef-4dbb-4094-b333-52d1e0f06b5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OtherOperatingRealEstateLeasesMember_71818ed0-d5b0-4ef2-9121-2108a6ff4dee" xlink:href="oust-20241231.xsd#oust_OtherOperatingRealEstateLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_OtherOperatingRealEstateLeasesMember_71818ed0-d5b0-4ef2-9121-2108a6ff4dee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OfficeAndManufacturingSpaceInSanJoseCaliforniaMember_c1c9f49c-dd0b-4f5f-b7eb-212aa49429d4" xlink:href="oust-20241231.xsd#oust_OfficeAndManufacturingSpaceInSanJoseCaliforniaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_OfficeAndManufacturingSpaceInSanJoseCaliforniaMember_c1c9f49c-dd0b-4f5f-b7eb-212aa49429d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A350TreatBuildingLeaseMember_bb40450a-a4c3-4965-9429-78895425412c" xlink:href="oust-20241231.xsd#oust_A350TreatBuildingLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_A350TreatBuildingLeaseMember_bb40450a-a4c3-4965-9429-78895425412c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A274116thStreetLeaseMember_8521222b-3a6a-4a91-b84c-12403ec3aac2" xlink:href="oust-20241231.xsd#oust_A274116thStreetLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_A274116thStreetLeaseMember_8521222b-3a6a-4a91-b84c-12403ec3aac2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A5521HellyerAvenueLeaseMember_ef184f03-78db-4374-a7b7-9cda5b21be09" xlink:href="oust-20241231.xsd#oust_A5521HellyerAvenueLeaseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_555e24ce-4f83-4f61-8f18-1f47a2fcbfb6" xlink:to="loc_oust_A5521HellyerAvenueLeaseMember_ef184f03-78db-4374-a7b7-9cda5b21be09" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_72511c2f-2856-4a3a-9929-74537bdcfcb5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e48d0aa9-2782-4d0f-93ce-1b0a709854b9" xlink:to="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_72511c2f-2856-4a3a-9929-74537bdcfcb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_72511c2f-2856-4a3a-9929-74537bdcfcb5_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_72511c2f-2856-4a3a-9929-74537bdcfcb5" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_72511c2f-2856-4a3a-9929-74537bdcfcb5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_cb286a2a-f6d4-4319-8812-bb04df5d2b2d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MortgageLoansOnRealEstateNamePropertyTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis_72511c2f-2856-4a3a-9929-74537bdcfcb5" xlink:to="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_cb286a2a-f6d4-4319-8812-bb04df5d2b2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficeBuildingMember_30d8f41e-2817-4fe6-b5b9-263ff8bc6085" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_OfficeBuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_cb286a2a-f6d4-4319-8812-bb04df5d2b2d" xlink:to="loc_srt_OfficeBuildingMember_30d8f41e-2817-4fe6-b5b9-263ff8bc6085" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParkingMember_c3d81454-87a0-43c4-8dca-27a906d08677" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ParkingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_MortgageLoansOnRealEstateNamePropertyTypeDomain_cb286a2a-f6d4-4319-8812-bb04df5d2b2d" xlink:to="loc_us-gaap_ParkingMember_c3d81454-87a0-43c4-8dca-27a906d08677" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_e48d0aa9-2782-4d0f-93ce-1b0a709854b9" xlink:to="loc_srt_RangeAxis_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c" xlink:to="loc_srt_RangeMember_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_340a540e-7d42-4733-96ba-05f1ce0e6d2a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_21e58f0b-6b46-4f63-bbd8-0142adb5aa5c" xlink:to="loc_srt_RangeMember_340a540e-7d42-4733-96ba-05f1ce0e6d2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_2966596f-8fbf-4920-9550-b12b43d0886a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_340a540e-7d42-4733-96ba-05f1ce0e6d2a" xlink:to="loc_srt_MinimumMember_2966596f-8fbf-4920-9550-b12b43d0886a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_07b4deb5-440c-4371-a75c-201a7b684271" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_340a540e-7d42-4733-96ba-05f1ce0e6d2a" xlink:to="loc_srt_MaximumMember_07b4deb5-440c-4371-a75c-201a7b684271" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AreaOfRealEstateProperty_1208abe8-b660-461a-89b3-9157c042fa3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AreaOfRealEstateProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_AreaOfRealEstateProperty_1208abe8-b660-461a-89b3-9157c042fa3a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLeaseNumberOfLeaseAgreements_138fc8d6-ae14-4c25-a227-4dda15bcc50a" xlink:href="oust-20241231.xsd#oust_OperatingLeaseNumberOfLeaseAgreements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_OperatingLeaseNumberOfLeaseAgreements_138fc8d6-ae14-4c25-a227-4dda15bcc50a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_e9ac504b-312c-4b55-a898-1550c3a30c8d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_e9ac504b-312c-4b55-a898-1550c3a30c8d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_36356715-32e3-4437-bb14-2793d1809123" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_OperatingLeaseCost_36356715-32e3-4437-bb14-2793d1809123" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseImpairmentLoss_cc75df4b-901c-407b-ad7d-974ca923170c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_OperatingLeaseImpairmentLoss_cc75df4b-901c-407b-ad7d-974ca923170c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnTerminationOfLease_d4db0686-d14d-4823-940d-283e8c896cc5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnTerminationOfLease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_GainLossOnTerminationOfLease_d4db0686-d14d-4823-940d-283e8c896cc5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_2e72eb11-14dc-45ee-bba0-3e36cd45f820" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_2e72eb11-14dc-45ee-bba0-3e36cd45f820" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_LesseeOperatingLeaseBaseLeasePaymentForExtendedLeaseTerm_ee5aec25-8d2d-46f0-8ec5-8572245b1e38" xlink:href="oust-20241231.xsd#oust_LesseeOperatingLeaseBaseLeasePaymentForExtendedLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_LesseeOperatingLeaseBaseLeasePaymentForExtendedLeaseTerm_ee5aec25-8d2d-46f0-8ec5-8572245b1e38" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLeaseLiabilityAdjustment_6d42c0c9-ed84-4347-8370-f5b6f39f9395" xlink:href="oust-20241231.xsd#oust_OperatingLeaseLiabilityAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_OperatingLeaseLiabilityAdjustment_6d42c0c9-ed84-4347-8370-f5b6f39f9395" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLeaseRightOfUseAssetAdjustment_d3c3ffc3-4b73-4438-bc08-2619b1a8bfe8" xlink:href="oust-20241231.xsd#oust_OperatingLeaseRightOfUseAssetAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_OperatingLeaseRightOfUseAssetAdjustment_d3c3ffc3-4b73-4438-bc08-2619b1a8bfe8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_49e394f3-061e-41d5-89e8-a2d7d2bb5b39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_49e394f3-061e-41d5-89e8-a2d7d2bb5b39" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_6ef44d6f-2e67-438a-a554-527f32a8a998" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_OperatingLeaseLiability_6ef44d6f-2e67-438a-a554-527f32a8a998" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseDiscountRate_1610742a-dbe8-44fc-a00b-38d157ba5b4e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_LesseeOperatingLeaseDiscountRate_1610742a-dbe8-44fc-a00b-38d157ba5b4e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_LesseeOperatingLeaseIncreaseInBaseLeasePayment_2f2d1172-0369-4070-8b0d-a87eba54077e" xlink:href="oust-20241231.xsd#oust_LesseeOperatingLeaseIncreaseInBaseLeasePayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_LesseeOperatingLeaseIncreaseInBaseLeasePayment_2f2d1172-0369-4070-8b0d-a87eba54077e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3c5eef6a-df5e-459d-884f-f13fa2b9b57e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_3c5eef6a-df5e-459d-884f-f13fa2b9b57e" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLeaseFixedLeaseExpense_48a50df4-86e7-45be-82d0-e721e3ffacb6" xlink:href="oust-20241231.xsd#oust_OperatingLeaseFixedLeaseExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_oust_OperatingLeaseFixedLeaseExpense_48a50df4-86e7-45be-82d0-e721e3ffacb6" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_40ee87a3-56bb-4b26-91f2-03bdbf191c94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableLeaseCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_VariableLeaseCost_40ee87a3-56bb-4b26-91f2-03bdbf191c94" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_d0df5170-5517-4a59-af22-fd396ee1d9e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_5469ec19-2cd0-4333-95bd-cecb2154a655" xlink:to="loc_us-gaap_OperatingLeasePayments_d0df5170-5517-4a59-af22-fd396ee1d9e5" xlink:type="arc" order="17"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_fe088960-05ac-44b3-b3d8-b7e0d915d21f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:to="loc_srt_CounterpartyNameAxis_fe088960-05ac-44b3-b3d8-b7e0d915d21f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_fe088960-05ac-44b3-b3d8-b7e0d915d21f_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_fe088960-05ac-44b3-b3d8-b7e0d915d21f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_fe088960-05ac-44b3-b3d8-b7e0d915d21f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bc75c552-8ebd-41db-a1e7-4b4d25a5bb4d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_fe088960-05ac-44b3-b3d8-b7e0d915d21f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bc75c552-8ebd-41db-a1e7-4b4d25a5bb4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ThirdPartyContractManufacturerMember_5335f59d-82a4-4ad2-88e9-7770335f8bd1" xlink:href="oust-20241231.xsd#oust_ThirdPartyContractManufacturerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bc75c552-8ebd-41db-a1e7-4b4d25a5bb4d" xlink:to="loc_oust_ThirdPartyContractManufacturerMember_5335f59d-82a4-4ad2-88e9-7770335f8bd1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OtherVendorsMember_2488958f-0bce-4826-8798-eb30a303897f" xlink:href="oust-20241231.xsd#oust_OtherVendorsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_bc75c552-8ebd-41db-a1e7-4b4d25a5bb4d" xlink:to="loc_oust_OtherVendorsMember_2488958f-0bce-4826-8798-eb30a303897f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_e72e838a-62ee-4869-aa22-b447033f5360" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:to="loc_srt_LitigationCaseAxis_e72e838a-62ee-4869-aa22-b447033f5360" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_e72e838a-62ee-4869-aa22-b447033f5360_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_e72e838a-62ee-4869-aa22-b447033f5360" xlink:to="loc_srt_LitigationCaseTypeDomain_e72e838a-62ee-4869-aa22-b447033f5360_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_3b34ec5d-a27e-4a93-af2d-84cdc913cd86" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_e72e838a-62ee-4869-aa22-b447033f5360" xlink:to="loc_srt_LitigationCaseTypeDomain_3b34ec5d-a27e-4a93-af2d-84cdc913cd86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_NickV.VelodyneLidarInc.EtAl.Member_44c9933b-6c72-4e3d-9967-cdf14e7eee23" xlink:href="oust-20241231.xsd#oust_NickV.VelodyneLidarInc.EtAl.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_3b34ec5d-a27e-4a93-af2d-84cdc913cd86" xlink:to="loc_oust_NickV.VelodyneLidarInc.EtAl.Member_44c9933b-6c72-4e3d-9967-cdf14e7eee23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MoradpourV.VelodyneLidarInc.EtAl.Member_c7db76ea-ef8e-432d-85f0-ef31efc3208e" xlink:href="oust-20241231.xsd#oust_MoradpourV.VelodyneLidarInc.EtAl.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_3b34ec5d-a27e-4a93-af2d-84cdc913cd86" xlink:to="loc_oust_MoradpourV.VelodyneLidarInc.EtAl.Member_c7db76ea-ef8e-432d-85f0-ef31efc3208e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_BergerV.GrafAcquisitionLLCEtAl.Member_fd816d80-ac7c-417a-8a9d-93975793f1d0" xlink:href="oust-20241231.xsd#oust_BergerV.GrafAcquisitionLLCEtAl.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_3b34ec5d-a27e-4a93-af2d-84cdc913cd86" xlink:to="loc_oust_BergerV.GrafAcquisitionLLCEtAl.Member_fd816d80-ac7c-417a-8a9d-93975793f1d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_d2ffd976-aeaa-426d-8037-951b6492a593" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_d2ffd976-aeaa-426d-8037-951b6492a593" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_d2ffd976-aeaa-426d-8037-951b6492a593_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_d2ffd976-aeaa-426d-8037-951b6492a593" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_d2ffd976-aeaa-426d-8037-951b6492a593_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_9c3f71fe-8199-43e6-810e-fb5550268baf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_d2ffd976-aeaa-426d-8037-951b6492a593" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_9c3f71fe-8199-43e6-810e-fb5550268baf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_2b7fe26f-7ae4-4673-90d0-c1fb85fa96f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_9c3f71fe-8199-43e6-810e-fb5550268baf" xlink:to="loc_us-gaap_SubsequentEventMember_2b7fe26f-7ae4-4673-90d0-c1fb85fa96f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusAxis_6377c973-556a-4008-94d5-6d72fc16b14e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_7237a1ad-802d-427e-9a5b-4c3f7f9bbf97" xlink:to="loc_us-gaap_LitigationStatusAxis_6377c973-556a-4008-94d5-6d72fc16b14e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_6377c973-556a-4008-94d5-6d72fc16b14e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_6377c973-556a-4008-94d5-6d72fc16b14e" xlink:to="loc_us-gaap_LitigationStatusDomain_6377c973-556a-4008-94d5-6d72fc16b14e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationStatusDomain_5084e4a6-5b1f-4c6d-95ae-e6c74c9a20e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_6377c973-556a-4008-94d5-6d72fc16b14e" xlink:to="loc_us-gaap_LitigationStatusDomain_5084e4a6-5b1f-4c6d-95ae-e6c74c9a20e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SettledLitigationMember_1e7fcfa9-783f-4d2f-8107-0a98344ba431" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SettledLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_5084e4a6-5b1f-4c6d-95ae-e6c74c9a20e4" xlink:to="loc_us-gaap_SettledLitigationMember_1e7fcfa9-783f-4d2f-8107-0a98344ba431" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_386528a1-0c6b-44ab-ad2e-3b21d29d8773" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_386528a1-0c6b-44ab-ad2e-3b21d29d8773" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_eb1eccb6-504e-4c36-a0ac-fac31084964a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_eb1eccb6-504e-4c36-a0ac-fac31084964a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_NumberOfCurrentOrFormerDirectorsFiledAgainstInLawsuits_48e3667b-473a-42dd-bd50-95f1b1550506" xlink:href="oust-20241231.xsd#oust_NumberOfCurrentOrFormerDirectorsFiledAgainstInLawsuits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_oust_NumberOfCurrentOrFormerDirectorsFiledAgainstInLawsuits_48e3667b-473a-42dd-bd50-95f1b1550506" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_NumberOfOtherEntitiesFiledAgainstInLawsuits_cb6b8dfd-3221-4f42-bcca-7f30548a0540" xlink:href="oust-20241231.xsd#oust_NumberOfOtherEntitiesFiledAgainstInLawsuits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_oust_NumberOfOtherEntitiesFiledAgainstInLawsuits_cb6b8dfd-3221-4f42-bcca-7f30548a0540" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_5468ad0a-3d44-4d33-94b0-873152ee32c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationSettlementAmountAwardedToOtherParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LitigationSettlementAmountAwardedToOtherParty_5468ad0a-3d44-4d33-94b0-873152ee32c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_LossContingencyEstimatedRecoveryFromThirdPartyAmount_5fe03ebe-a1d2-42ae-98fa-31661db7a6d2" xlink:href="oust-20241231.xsd#oust_LossContingencyEstimatedRecoveryFromThirdPartyAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_oust_LossContingencyEstimatedRecoveryFromThirdPartyAmount_5fe03ebe-a1d2-42ae-98fa-31661db7a6d2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_8f8814f0-531c-44ac-9511-ee19d6aebf96" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_8f8814f0-531c-44ac-9511-ee19d6aebf96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceSettlementsReceivableCurrent_9f1a3b07-855a-4f8c-8aee-77206e18ce32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InsuranceSettlementsReceivableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_InsuranceSettlementsReceivableCurrent_9f1a3b07-855a-4f8c-8aee-77206e18ce32" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LitigationSettlementExpense_10cde3d7-90af-4b88-b912-cf2c6bad8c36" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LitigationSettlementExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LitigationSettlementExpense_10cde3d7-90af-4b88-b912-cf2c6bad8c36" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLegalSettlements_e39e6c0f-f91c-4d94-b0c8-c7fe56d124f1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsForLegalSettlements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_PaymentsForLegalSettlements_e39e6c0f-f91c-4d94-b0c8-c7fe56d124f1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInsuranceSettlementsReceivable_d63ea2d9-2c55-4d5c-9aaf-3a4944f72e09" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInInsuranceSettlementsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_IncreaseDecreaseInInsuranceSettlementsReceivable_d63ea2d9-2c55-4d5c-9aaf-3a4944f72e09" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_3ad8872a-5b9b-4b02-a0d8-4b35ca38d694" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_3ad8872a-5b9b-4b02-a0d8-4b35ca38d694" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_LossContingencyNumberOfRespondents_83357c02-86d3-4a6a-9d97-bffe754d0bd6" xlink:href="oust-20241231.xsd#oust_LossContingencyNumberOfRespondents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_a8689392-7095-4106-a7b5-a1f148f9774f" xlink:to="loc_oust_LossContingencyNumberOfRespondents_83357c02-86d3-4a6a-9d97-bffe754d0bd6" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/CommonStockDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#CommonStockDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/CommonStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_69161c64-285a-403f-ab4e-0920afadb99a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_69161c64-285a-403f-ab4e-0920afadb99a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_3ff55175-a686-47bb-9682-f913c363312a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_69161c64-285a-403f-ab4e-0920afadb99a" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_3ff55175-a686-47bb-9682-f913c363312a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_3ff55175-a686-47bb-9682-f913c363312a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_3ff55175-a686-47bb-9682-f913c363312a" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_3ff55175-a686-47bb-9682-f913c363312a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50219b12-a73d-474f-be60-0bc576dc0050" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_3ff55175-a686-47bb-9682-f913c363312a" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50219b12-a73d-474f-be60-0bc576dc0050" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_AtTheMarketProgramMember_db7e278c-a6cc-4785-b69c-c84f186bb225" xlink:href="oust-20241231.xsd#oust_AtTheMarketProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_50219b12-a73d-474f-be60-0bc576dc0050" xlink:to="loc_oust_AtTheMarketProgramMember_db7e278c-a6cc-4785-b69c-c84f186bb225" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_f9347f46-46dc-4402-827f-a0f25a82792e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_f9347f46-46dc-4402-827f-a0f25a82792e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_a1a6ecfc-9def-4f7c-bb30-e1ef9da6e474" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_a1a6ecfc-9def-4f7c-bb30-e1ef9da6e474" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_26e1edf5-dddf-4cf8-b2d5-462c862584a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_26e1edf5-dddf-4cf8-b2d5-462c862584a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_20f7ec01-0f42-404e-9d6c-071d5822f892" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_20f7ec01-0f42-404e-9d6c-071d5822f892" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CommonStockVotingRightsNumberOfVotesPerShare_abf59a91-e7dc-42a5-a33d-98788a26df9a" xlink:href="oust-20241231.xsd#oust_CommonStockVotingRightsNumberOfVotesPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_oust_CommonStockVotingRightsNumberOfVotesPerShare_abf59a91-e7dc-42a5-a33d-98788a26df9a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockAuthorizedAmount_2c3cd650-150c-497d-ae0e-72c0872df941" xlink:href="oust-20241231.xsd#oust_SaleOfStockAuthorizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_oust_SaleOfStockAuthorizedAmount_2c3cd650-150c-497d-ae0e-72c0872df941" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_607da6c3-1b83-4824-b5ee-ecbb68b148a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_607da6c3-1b83-4824-b5ee-ecbb68b148a2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockWeightedAverageStockPricePerShare_397e6f12-0384-492c-abe8-773c4c2543de" xlink:href="oust-20241231.xsd#oust_SaleOfStockWeightedAverageStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_oust_SaleOfStockWeightedAverageStockPricePerShare_397e6f12-0384-492c-abe8-773c4c2543de" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_fa42d692-7e4e-4e80-9ea2-287db7611dd2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_fa42d692-7e4e-4e80-9ea2-287db7611dd2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SaleOfStockRemainingAuthorizedAmount_c0b42dc2-c8cc-4498-a6cf-7e93ab7c215a" xlink:href="oust-20241231.xsd#oust_SaleOfStockRemainingAuthorizedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_9503d2b9-635f-48a5-8606-1817d1613969" xlink:to="loc_oust_SaleOfStockRemainingAuthorizedAmount_c0b42dc2-c8cc-4498-a6cf-7e93ab7c215a" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_bec895d0-0ea3-408a-bba5-97d4bebd8a0c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_AwardTypeAxis_bec895d0-0ea3-408a-bba5-97d4bebd8a0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bec895d0-0ea3-408a-bba5-97d4bebd8a0c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_bec895d0-0ea3-408a-bba5-97d4bebd8a0c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bec895d0-0ea3-408a-bba5-97d4bebd8a0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bced5a3d-3f81-4e9c-97bd-2b497e29adc0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_bec895d0-0ea3-408a-bba5-97d4bebd8a0c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bced5a3d-3f81-4e9c-97bd-2b497e29adc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_7bcabd47-1259-4e33-8e8b-89a472d67a94" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bced5a3d-3f81-4e9c-97bd-2b497e29adc0" xlink:to="loc_us-gaap_EmployeeStockOptionMember_7bcabd47-1259-4e33-8e8b-89a472d67a94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_10b465f0-7727-4e27-9d59-7eea0de0547b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bced5a3d-3f81-4e9c-97bd-2b497e29adc0" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_10b465f0-7727-4e27-9d59-7eea0de0547b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_4a569870-6095-4996-8e44-0800dd456be2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bced5a3d-3f81-4e9c-97bd-2b497e29adc0" xlink:to="loc_us-gaap_RestrictedStockMember_4a569870-6095-4996-8e44-0800dd456be2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_2cd916fe-fb62-4c49-9348-3286b2c7106e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_PlanNameAxis_2cd916fe-fb62-4c49-9348-3286b2c7106e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_2cd916fe-fb62-4c49-9348-3286b2c7106e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_2cd916fe-fb62-4c49-9348-3286b2c7106e" xlink:to="loc_us-gaap_PlanNameDomain_2cd916fe-fb62-4c49-9348-3286b2c7106e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_369be7a1-0901-40d0-92fb-bf4eb2c06c3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_2cd916fe-fb62-4c49-9348-3286b2c7106e" xlink:to="loc_us-gaap_PlanNameDomain_369be7a1-0901-40d0-92fb-bf4eb2c06c3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A2015StockPlanMember_ba018a36-2b10-4af2-b6a4-eadafd6a32ba" xlink:href="oust-20241231.xsd#oust_A2015StockPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_369be7a1-0901-40d0-92fb-bf4eb2c06c3f" xlink:to="loc_oust_A2015StockPlanMember_ba018a36-2b10-4af2-b6a4-eadafd6a32ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A2021IncentiveAwardPlanMember_53c15982-f874-4caf-b54d-50977baef5ce" xlink:href="oust-20241231.xsd#oust_A2021IncentiveAwardPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_369be7a1-0901-40d0-92fb-bf4eb2c06c3f" xlink:to="loc_oust_A2021IncentiveAwardPlanMember_53c15982-f874-4caf-b54d-50977baef5ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_A2022EmployeeStockPurchasePlanMember_05eb0fec-41d6-4a77-937e-d322f9d702c0" xlink:href="oust-20241231.xsd#oust_A2022EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_369be7a1-0901-40d0-92fb-bf4eb2c06c3f" xlink:to="loc_oust_A2022EmployeeStockPurchasePlanMember_05eb0fec-41d6-4a77-937e-d322f9d702c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_669eb16f-5496-4420-8481-5d352fc0fd9e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_srt_RangeAxis_669eb16f-5496-4420-8481-5d352fc0fd9e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_669eb16f-5496-4420-8481-5d352fc0fd9e_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_669eb16f-5496-4420-8481-5d352fc0fd9e" xlink:to="loc_srt_RangeMember_669eb16f-5496-4420-8481-5d352fc0fd9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_334b2fb4-4725-4187-a2b9-3f8342c24b27" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_669eb16f-5496-4420-8481-5d352fc0fd9e" xlink:to="loc_srt_RangeMember_334b2fb4-4725-4187-a2b9-3f8342c24b27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_575e0080-f423-4830-b123-eb2e447775af" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_334b2fb4-4725-4187-a2b9-3f8342c24b27" xlink:to="loc_srt_MaximumMember_575e0080-f423-4830-b123-eb2e447775af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusAxis_cd5ee883-9ac1-4256-ae87-35adea8018f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GranteeStatusAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_GranteeStatusAxis_cd5ee883-9ac1-4256-ae87-35adea8018f8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_cd5ee883-9ac1-4256-ae87-35adea8018f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GranteeStatusAxis_cd5ee883-9ac1-4256-ae87-35adea8018f8" xlink:to="loc_us-gaap_GranteeStatusDomain_cd5ee883-9ac1-4256-ae87-35adea8018f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GranteeStatusDomain_62016dae-fb0c-4a75-bb14-1e65dc9858d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GranteeStatusDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GranteeStatusAxis_cd5ee883-9ac1-4256-ae87-35adea8018f8" xlink:to="loc_us-gaap_GranteeStatusDomain_62016dae-fb0c-4a75-bb14-1e65dc9858d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedPaymentArrangement10ShareholderMember_8dbd0330-866f-4429-843c-3c173c9dd919" xlink:href="oust-20241231.xsd#oust_ShareBasedPaymentArrangement10ShareholderMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_62016dae-fb0c-4a75-bb14-1e65dc9858d2" xlink:to="loc_oust_ShareBasedPaymentArrangement10ShareholderMember_8dbd0330-866f-4429-843c-3c173c9dd919" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_b5bcbfce-911f-4141-8902-6cdd8d967eda" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedPaymentArrangementEmployeeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GranteeStatusDomain_62016dae-fb0c-4a75-bb14-1e65dc9858d2" xlink:to="loc_us-gaap_ShareBasedPaymentArrangementEmployeeMember_b5bcbfce-911f-4141-8902-6cdd8d967eda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_b6f00a5f-edaf-4c42-8b59-91ba8186e615" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_VestingAxis_b6f00a5f-edaf-4c42-8b59-91ba8186e615" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_b6f00a5f-edaf-4c42-8b59-91ba8186e615_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_b6f00a5f-edaf-4c42-8b59-91ba8186e615" xlink:to="loc_us-gaap_VestingDomain_b6f00a5f-edaf-4c42-8b59-91ba8186e615_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_3796853a-27ae-4707-ac38-00bcce95a5a8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_b6f00a5f-edaf-4c42-8b59-91ba8186e615" xlink:to="loc_us-gaap_VestingDomain_3796853a-27ae-4707-ac38-00bcce95a5a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_1ac256cf-ced0-42cb-82dd-92583c4b1860" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_3796853a-27ae-4707-ac38-00bcce95a5a8" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_1ac256cf-ced0-42cb-82dd-92583c4b1860" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedPaymentArrangementMonthlyVestingForThirtySixMonthMember_9f40c62d-6c57-40c3-a7cb-da42394fdbfc" xlink:href="oust-20241231.xsd#oust_ShareBasedPaymentArrangementMonthlyVestingForThirtySixMonthMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_3796853a-27ae-4707-ac38-00bcce95a5a8" xlink:to="loc_oust_ShareBasedPaymentArrangementMonthlyVestingForThirtySixMonthMember_9f40c62d-6c57-40c3-a7cb-da42394fdbfc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_790479d7-934c-4d7e-87b7-cb12bb2c18d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_790479d7-934c-4d7e-87b7-cb12bb2c18d7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_790479d7-934c-4d7e-87b7-cb12bb2c18d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_790479d7-934c-4d7e-87b7-cb12bb2c18d7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_790479d7-934c-4d7e-87b7-cb12bb2c18d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4e5deb69-38b4-499f-b6b1-2008623c221d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_790479d7-934c-4d7e-87b7-cb12bb2c18d7" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4e5deb69-38b4-499f-b6b1-2008623c221d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_SensePhotonicsIncMember_5a1493cb-2e66-4f28-8476-b054c8f67ee2" xlink:href="oust-20241231.xsd#oust_SensePhotonicsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4e5deb69-38b4-499f-b6b1-2008623c221d" xlink:to="loc_oust_SensePhotonicsIncMember_5a1493cb-2e66-4f28-8476-b054c8f67ee2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_VelodyneLidarIncMember_b2ca7473-cef2-409e-8d5f-a0dd3325b6c7" xlink:href="oust-20241231.xsd#oust_VelodyneLidarIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4e5deb69-38b4-499f-b6b1-2008623c221d" xlink:to="loc_oust_VelodyneLidarIncMember_b2ca7473-cef2-409e-8d5f-a0dd3325b6c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_b5af6e20-31bc-4b62-ae0b-7f14675dadb2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_296dda35-cde9-4964-a327-2bb6442b1515" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_b5af6e20-31bc-4b62-ae0b-7f14675dadb2" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_b5af6e20-31bc-4b62-ae0b-7f14675dadb2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b5af6e20-31bc-4b62-ae0b-7f14675dadb2" xlink:to="loc_us-gaap_EquityComponentDomain_b5af6e20-31bc-4b62-ae0b-7f14675dadb2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_1ec116ce-4ebd-40bf-b96b-ef4de5f27e2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_b5af6e20-31bc-4b62-ae0b-7f14675dadb2" xlink:to="loc_us-gaap_EquityComponentDomain_1ec116ce-4ebd-40bf-b96b-ef4de5f27e2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_2d4f1811-1e85-40b6-be0a-20fbb946c0d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1ec116ce-4ebd-40bf-b96b-ef4de5f27e2c" xlink:to="loc_us-gaap_CommonStockMember_2d4f1811-1e85-40b6-be0a-20fbb946c0d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedPaymentArrangementNumberOfEquityIncentivePlans_e3c7698d-b341-4f93-b642-525c7f549955" xlink:href="oust-20241231.xsd#oust_ShareBasedPaymentArrangementNumberOfEquityIncentivePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedPaymentArrangementNumberOfEquityIncentivePlans_e3c7698d-b341-4f93-b642-525c7f549955" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_289cfbfe-867b-416e-9edc-05bf9a97b95b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_289cfbfe-867b-416e-9edc-05bf9a97b95b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumExercisePriceAsPercentageOfFairValueOfSharesOnGrantDate_efd89987-ed53-410c-99ba-610812cdda7b" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumExercisePriceAsPercentageOfFairValueOfSharesOnGrantDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardMinimumExercisePriceAsPercentageOfFairValueOfSharesOnGrantDate_efd89987-ed53-410c-99ba-610812cdda7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareholderOwnershipPercentage_078e5352-804c-4c2d-934d-7588dc1a1b05" xlink:href="oust-20241231.xsd#oust_ShareholderOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareholderOwnershipPercentage_078e5352-804c-4c2d-934d-7588dc1a1b05" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_910fd498-8721-4f32-a06c-dd17075c0e7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_910fd498-8721-4f32-a06c-dd17075c0e7f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6ae5f98e-7db3-447b-9f88-e39912a5e146" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_6ae5f98e-7db3-447b-9f88-e39912a5e146" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsVestedPercentage_18005b06-71e9-4e24-be4e-27c00628f71c" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsVestedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRightsVestedPercentage_18005b06-71e9-4e24-be4e-27c00628f71c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_8f4801a1-8dea-40eb-b1ba-c477691d826a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_8f4801a1-8dea-40eb-b1ba-c477691d826a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAuthorizedAnnualIncreasePercentage_30b26048-b8c3-47e5-843c-3166c81b7eb2" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAuthorizedAnnualIncreasePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseInNumberOfSharesAuthorizedAnnualIncreasePercentage_30b26048-b8c3-47e5-843c-3166c81b7eb2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_a4aca1af-9ce5-4251-9fb8-40e5ca5c26f4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_a4aca1af-9ce5-4251-9fb8-40e5ca5c26f4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_EmployeeStockPurchasePlanOfferingPeriod_bd231bb7-1d9a-4d96-b874-deb62eb13d7d" xlink:href="oust-20241231.xsd#oust_EmployeeStockPurchasePlanOfferingPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_EmployeeStockPurchasePlanOfferingPeriod_bd231bb7-1d9a-4d96-b874-deb62eb13d7d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod_f0817737-153d-49b0-95be-8dee544c26ac" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePeriod_f0817737-153d-49b0-95be-8dee544c26ac" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_44d40905-8421-42be-a50b-38fe68209887" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent_44d40905-8421-42be-a50b-38fe68209887" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_30b9861a-2c1b-4f7e-b10a-b325347d9787" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfSharesPerEmployee_30b9861a-2c1b-4f7e-b10a-b325347d9787" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_e0b34a87-9d59-4846-9e92-5d034eb56d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_e0b34a87-9d59-4846-9e92-5d034eb56d7e" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssuedPricePerShare_fd2bde6f-5c24-4224-973b-04f4f1072e4c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesIssuedPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_SharesIssuedPricePerShare_fd2bde6f-5c24-4224-973b-04f4f1072e4c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockPlans_fc063a99-3bc9-4f78-a668-a930fe448a77" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromStockPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_ProceedsFromStockPlans_fc063a99-3bc9-4f78-a668-a930fe448a77" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAssumedInBusinessCombination_743e0b5c-f763-42b8-a8d7-0b53674477d9" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAssumedInBusinessCombination"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAssumedInBusinessCombination_743e0b5c-f763-42b8-a8d7-0b53674477d9" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseDecreaseInSharesReservedForFutureIssuance_12e0c6b7-db02-4b21-a211-7c832690ab8e" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseDecreaseInSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseDecreaseInSharesReservedForFutureIssuance_12e0c6b7-db02-4b21-a211-7c832690ab8e" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_2c7c7888-05f0-427f-b234-479f0b873213" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_2c7c7888-05f0-427f-b234-479f0b873213" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_68a19c28-9398-4007-9f43-a32373d9c034" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_0381c1d7-e24d-4d13-9900-662e470c68a4" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_68a19c28-9398-4007-9f43-a32373d9c034" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationScheduleofStockbasedCompensationDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationScheduleofStockbasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationScheduleofStockbasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_10468f50-091a-49ba-9cae-752348a7daa2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_8fba3cea-ad2b-433e-ac1a-840ee0670dae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_10468f50-091a-49ba-9cae-752348a7daa2" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_8fba3cea-ad2b-433e-ac1a-840ee0670dae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_0bb586c4-fed7-4823-8cc7-01a99e347327" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_8fba3cea-ad2b-433e-ac1a-840ee0670dae" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_0bb586c4-fed7-4823-8cc7-01a99e347327" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_0bb586c4-fed7-4823-8cc7-01a99e347327_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_0bb586c4-fed7-4823-8cc7-01a99e347327" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_0bb586c4-fed7-4823-8cc7-01a99e347327_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_0bb586c4-fed7-4823-8cc7-01a99e347327" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_2b4f1f3f-8c65-495a-b67b-ecc794ee12ae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:to="loc_us-gaap_CostOfSalesMember_2b4f1f3f-8c65-495a-b67b-ecc794ee12ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_0fef057a-b0a9-475f-8757-fc90e0e66ddc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_0fef057a-b0a9-475f-8757-fc90e0e66ddc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpenseMember_4fad23aa-5264-4737-b228-2a862ed17492" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingAndMarketingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:to="loc_us-gaap_SellingAndMarketingExpenseMember_4fad23aa-5264-4737-b228-2a862ed17492" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_c7fdfeb7-87eb-409e-9bf6-586e6be31502" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_06aab9b3-9a8e-42d6-b8d8-42d16b82847e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_c7fdfeb7-87eb-409e-9bf6-586e6be31502" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_d01324c8-6be3-4cb5-afec-339fff05da5f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_10468f50-091a-49ba-9cae-752348a7daa2" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_d01324c8-6be3-4cb5-afec-339fff05da5f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationScheduleofStockCompensationExpensebyAwardTypeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationScheduleofStockCompensationExpensebyAwardTypeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationScheduleofStockCompensationExpensebyAwardTypeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_596f1367-34c3-4fe2-9605-a2060a4266ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3197c24-47dc-44c1-bad1-831e3f474837" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_596f1367-34c3-4fe2-9605-a2060a4266ac" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3197c24-47dc-44c1-bad1-831e3f474837" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a19fb79d-1167-4a5c-8b09-92244b5f3abf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f3197c24-47dc-44c1-bad1-831e3f474837" xlink:to="loc_us-gaap_AwardTypeAxis_a19fb79d-1167-4a5c-8b09-92244b5f3abf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a19fb79d-1167-4a5c-8b09-92244b5f3abf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a19fb79d-1167-4a5c-8b09-92244b5f3abf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a19fb79d-1167-4a5c-8b09-92244b5f3abf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a19fb79d-1167-4a5c-8b09-92244b5f3abf" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_41f985c8-6f24-46d6-a6ac-6ac43e957277" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_41f985c8-6f24-46d6-a6ac-6ac43e957277" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_754aea10-ad3c-4b68-98e9-0b7b93ae659b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:to="loc_us-gaap_EmployeeStockOptionMember_754aea10-ad3c-4b68-98e9-0b7b93ae659b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_99021b37-e3a6-4eaa-b33b-e7033822579a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:to="loc_us-gaap_EmployeeStockMember_99021b37-e3a6-4eaa-b33b-e7033822579a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_bb2bb56d-6f7b-488d-9674-72ecc04c0c7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_dc55e3c4-f1e6-405f-bc33-53fdeb2d9d5b" xlink:to="loc_us-gaap_RestrictedStockMember_bb2bb56d-6f7b-488d-9674-72ecc04c0c7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_d07d721e-97db-499d-aba3-66622e36cdca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_596f1367-34c3-4fe2-9605-a2060a4266ac" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_d07d721e-97db-499d-aba3-66622e36cdca" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationScheduleofStockOptionsOutstandingandExercisableDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationScheduleofStockOptionsOutstandingandExercisableDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationScheduleofStockOptionsOutstandingandExercisableDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_63c7eb2a-eb13-49b5-9a7f-537552c3a7ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_63c7eb2a-eb13-49b5-9a7f-537552c3a7ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_eaf0ac28-0f8e-4459-a8f0-544fe297c47b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_63c7eb2a-eb13-49b5-9a7f-537552c3a7ab" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_eaf0ac28-0f8e-4459-a8f0-544fe297c47b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_eaf0ac28-0f8e-4459-a8f0-544fe297c47b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_eaf0ac28-0f8e-4459-a8f0-544fe297c47b" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_eaf0ac28-0f8e-4459-a8f0-544fe297c47b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis_eaf0ac28-0f8e-4459-a8f0-544fe297c47b" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ExercisePriceRangeOneMember_5fa2b84e-62d6-4afb-8b7c-0d828aae3dd3" xlink:href="oust-20241231.xsd#oust_ExercisePriceRangeOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:to="loc_oust_ExercisePriceRangeOneMember_5fa2b84e-62d6-4afb-8b7c-0d828aae3dd3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ExercisePriceRangeTwoMember_96677062-e3f0-4c84-9014-8c2a7080248b" xlink:href="oust-20241231.xsd#oust_ExercisePriceRangeTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:to="loc_oust_ExercisePriceRangeTwoMember_96677062-e3f0-4c84-9014-8c2a7080248b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ExercisePriceRangeThreeMember_2091e814-04d0-4d08-84f1-7e955f7e11bd" xlink:href="oust-20241231.xsd#oust_ExercisePriceRangeThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:to="loc_oust_ExercisePriceRangeThreeMember_2091e814-04d0-4d08-84f1-7e955f7e11bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ExercisePriceRangeFourMember_bff0368a-f1d6-49c4-b194-a3d69ab090fd" xlink:href="oust-20241231.xsd#oust_ExercisePriceRangeFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_c77c4546-9d15-4630-a308-2cbaab00c6d7" xlink:to="loc_oust_ExercisePriceRangeFourMember_bff0368a-f1d6-49c4-b194-a3d69ab090fd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_46894fe7-df37-4a16-96bf-ef3e06e45356" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_46894fe7-df37-4a16-96bf-ef3e06e45356" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_769f824b-d5e3-40c3-a155-4bc5803171e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_769f824b-d5e3-40c3-a155-4bc5803171e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_6cadc11e-df5e-4547-b135-63e0bde6854d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_6cadc11e-df5e-4547-b135-63e0bde6854d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_c0fe51ac-f9ce-442f-9d98-ff6153516e08" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_c0fe51ac-f9ce-442f-9d98-ff6153516e08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_fe33576c-fdd9-424a-b561-18b5113be671" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_b12b1f00-7994-4e9a-98dd-7cb44b7fff22" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_fe33576c-fdd9-424a-b561-18b5113be671" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationScheduleofRestrictedStockUnitsActivityDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationScheduleofRestrictedStockUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationScheduleofRestrictedStockUnitsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a8c87018-9d70-43be-bf97-02e7c7e37f64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58cdc81d-fedf-4334-906e-b9541f2077ff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a8c87018-9d70-43be-bf97-02e7c7e37f64" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58cdc81d-fedf-4334-906e-b9541f2077ff" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_df191b24-d14f-4b6e-8aa2-29e8227d54fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_58cdc81d-fedf-4334-906e-b9541f2077ff" xlink:to="loc_us-gaap_AwardTypeAxis_df191b24-d14f-4b6e-8aa2-29e8227d54fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df191b24-d14f-4b6e-8aa2-29e8227d54fe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_df191b24-d14f-4b6e-8aa2-29e8227d54fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_df191b24-d14f-4b6e-8aa2-29e8227d54fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e7bf6e8e-24e2-4ec5-9c8e-bd62a190095b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_df191b24-d14f-4b6e-8aa2-29e8227d54fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e7bf6e8e-24e2-4ec5-9c8e-bd62a190095b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_59dba629-3e3b-4128-b3f0-6f70cf87abc7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e7bf6e8e-24e2-4ec5-9c8e-bd62a190095b" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_59dba629-3e3b-4128-b3f0-6f70cf87abc7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a8c87018-9d70-43be-bf97-02e7c7e37f64" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_54290b91-16ff-44b4-a7f8-ae5a38ea9063" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_54290b91-16ff-44b4-a7f8-ae5a38ea9063" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ada80bbc-8c7e-4f6d-a70a-1db36bb92004" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ada80bbc-8c7e-4f6d-a70a-1db36bb92004" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCanceledInPeriod_64d716db-ae1e-40a6-8e17-1237112ce754" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCanceledInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCanceledInPeriod_64d716db-ae1e-40a6-8e17-1237112ce754" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_73df82f4-fb0a-452b-9a5f-701be812fcb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_90020b67-9590-441c-ac7f-3d717957f8d4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_73df82f4-fb0a-452b-9a5f-701be812fcb9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_8d3647ef-7019-4227-9655-dee2c4c453b6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a8c87018-9d70-43be-bf97-02e7c7e37f64" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fcf6daa8-79c7-4f0e-9149-e3ff438f4a23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_fcf6daa8-79c7-4f0e-9149-e3ff438f4a23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ac67d619-b409-4908-a824-59ed9576060b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_ac67d619-b409-4908-a824-59ed9576060b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancellationsWeightedAverageGrantDateFairValue_bac3cbac-3c94-46c7-bdae-7e17dc0432f0" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancellationsWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancellationsWeightedAverageGrantDateFairValue_bac3cbac-3c94-46c7-bdae-7e17dc0432f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_5f2145ce-cb63-4c0f-b310-d870f82380ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_33322441-dfd8-45df-b288-ff4fc6b19272" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_5f2145ce-cb63-4c0f-b310-d870f82380ac" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_0eb29d21-b4b2-4cbc-91b9-ac6f48e8ddfb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/StockbasedCompensationScheduleofNonvestedRestrictedStockAwardsActivityDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#StockbasedCompensationScheduleofNonvestedRestrictedStockAwardsActivityDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/StockbasedCompensationScheduleofNonvestedRestrictedStockAwardsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5a226d38-9079-4cbf-b9f6-ec4232e3fa80" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9bf826f0-2bb9-47a9-afcb-cef84357a44b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5a226d38-9079-4cbf-b9f6-ec4232e3fa80" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9bf826f0-2bb9-47a9-afcb-cef84357a44b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_704b4439-a4bf-4793-a53a-4c84a5c92182" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_9bf826f0-2bb9-47a9-afcb-cef84357a44b" xlink:to="loc_us-gaap_AwardTypeAxis_704b4439-a4bf-4793-a53a-4c84a5c92182" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_704b4439-a4bf-4793-a53a-4c84a5c92182_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_704b4439-a4bf-4793-a53a-4c84a5c92182" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_704b4439-a4bf-4793-a53a-4c84a5c92182_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30882970-68a0-415b-acdf-b55a30925820" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_704b4439-a4bf-4793-a53a-4c84a5c92182" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30882970-68a0-415b-acdf-b55a30925820" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_ff2cbd47-1e92-4ea2-9073-7eaa706497d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_30882970-68a0-415b-acdf-b55a30925820" xlink:to="loc_us-gaap_RestrictedStockMember_ff2cbd47-1e92-4ea2-9073-7eaa706497d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_52d45465-edf7-445d-8673-b2e409de89fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5a226d38-9079-4cbf-b9f6-ec4232e3fa80" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_52d45465-edf7-445d-8673-b2e409de89fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f396eb7b-1a93-4b6d-89d2-594ececd7b22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_52d45465-edf7-445d-8673-b2e409de89fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_f396eb7b-1a93-4b6d-89d2-594ececd7b22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_c4d5b36b-ac8e-4697-89e9-d37c9836b289" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_52d45465-edf7-445d-8673-b2e409de89fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_c4d5b36b-ac8e-4697-89e9-d37c9836b289" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9609853b-0b42-4ea3-8f7f-8982f2b9fe47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_52d45465-edf7-445d-8673-b2e409de89fe" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9609853b-0b42-4ea3-8f7f-8982f2b9fe47" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_5774bdbb-3d2d-47d1-8de7-22549e9898f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2b53b1d4-804d-4599-beac-98bc631166b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5a226d38-9079-4cbf-b9f6-ec4232e3fa80" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2b53b1d4-804d-4599-beac-98bc631166b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2aa58b26-3348-44ca-8295-d77b6a9fccb0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2b53b1d4-804d-4599-beac-98bc631166b4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_2aa58b26-3348-44ca-8295-d77b6a9fccb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3c5e7fd9-3a9f-4c0e-b353-0b6db1ef796d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2b53b1d4-804d-4599-beac-98bc631166b4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_3c5e7fd9-3a9f-4c0e-b353-0b6db1ef796d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_9e6632ce-dfbe-42d3-9320-b55bfb54c121" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2b53b1d4-804d-4599-beac-98bc631166b4" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_9e6632ce-dfbe-42d3-9320-b55bfb54c121" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_9a02b821-23c2-46d9-8a12-bb43f8e55b14" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/EmployeeBenefitPlanDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#EmployeeBenefitPlanDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/EmployeeBenefitPlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_d4c6bc4d-4a32-4c28-8267-a902f0c5c535" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedContributionPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanTable_2ddd727b-9ab6-4428-b030-651f7e29b564" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedContributionPlanTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_d4c6bc4d-4a32-4c28-8267-a902f0c5c535" xlink:to="loc_us-gaap_DefinedContributionPlanTable_2ddd727b-9ab6-4428-b030-651f7e29b564" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_5df31f56-a37f-472b-9106-f7d7152f2c9d" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DefinedContributionPlanTable_2ddd727b-9ab6-4428-b030-651f7e29b564" xlink:to="loc_srt_RangeAxis_5df31f56-a37f-472b-9106-f7d7152f2c9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5df31f56-a37f-472b-9106-f7d7152f2c9d_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5df31f56-a37f-472b-9106-f7d7152f2c9d" xlink:to="loc_srt_RangeMember_5df31f56-a37f-472b-9106-f7d7152f2c9d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_1b478b11-038c-4140-9c7d-d8b3b2ac8d83" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5df31f56-a37f-472b-9106-f7d7152f2c9d" xlink:to="loc_srt_RangeMember_1b478b11-038c-4140-9c7d-d8b3b2ac8d83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_a000f6c6-af2b-4934-a9ac-b287641808e3" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_1b478b11-038c-4140-9c7d-d8b3b2ac8d83" xlink:to="loc_srt_MaximumMember_a000f6c6-af2b-4934-a9ac-b287641808e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_e8f1d908-89ef-4efe-9c17-bc652f8ddde7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_d4c6bc4d-4a32-4c28-8267-a902f0c5c535" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch_e8f1d908-89ef-4efe-9c17-bc652f8ddde7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_5c60d0f6-d007-4642-8554-60b508a4e22a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPlanDisclosureLineItems_d4c6bc4d-4a32-4c28-8267-a902f0c5c535" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_5c60d0f6-d007-4642-8554-60b508a4e22a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/NetLossPerCommonShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofNetLossPerCommonShareDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#NetLossPerCommonShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofNetLossPerCommonShareDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/NetLossPerCommonShareScheduleofAntidilutiveSecuritiesExcludedfromComputationofNetLossPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_f33db14a-a850-43c3-88d2-c6decbd2cc89" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_33d9a648-6733-47dc-9781-fd3b45832a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_f33db14a-a850-43c3-88d2-c6decbd2cc89" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_33d9a648-6733-47dc-9781-fd3b45832a2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_290548d1-0d59-40b5-8b3b-349fad24f86b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_33d9a648-6733-47dc-9781-fd3b45832a2d" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_290548d1-0d59-40b5-8b3b-349fad24f86b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_290548d1-0d59-40b5-8b3b-349fad24f86b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_290548d1-0d59-40b5-8b3b-349fad24f86b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_290548d1-0d59-40b5-8b3b-349fad24f86b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_290548d1-0d59-40b5-8b3b-349fad24f86b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOptionsToPurchaseCommonStockMember_b2544468-58cc-48b6-87cc-db4d9c3b35e4" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOptionsToPurchaseCommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOptionsToPurchaseCommonStockMember_b2544468-58cc-48b6-87cc-db4d9c3b35e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_PublicAndPrivateCommonStockWarrantsMember_1745d759-2f67-41fe-a743-e186900e1fcd" xlink:href="oust-20241231.xsd#oust_PublicAndPrivateCommonStockWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_oust_PublicAndPrivateCommonStockWarrantsMember_1745d759-2f67-41fe-a743-e186900e1fcd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_df1137bf-b51c-4770-a430-de4f1a5165f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_df1137bf-b51c-4770-a430-de4f1a5165f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedEarlyExercisedCommonStockOptionsMember_8032e8f2-c0c7-43a0-a6c6-f8f6b627d501" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedEarlyExercisedCommonStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsUnvestedEarlyExercisedCommonStockOptionsMember_8032e8f2-c0c7-43a0-a6c6-f8f6b627d501" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockMember_29b93452-880e-4f23-9a53-d9604fa11b38" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_us-gaap_EmployeeStockMember_29b93452-880e-4f23-9a53-d9604fa11b38" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedStockAwardMember_c7fd6c5d-810c-45af-999a-368bbacdf4b1" xlink:href="oust-20241231.xsd#oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedStockAwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f1ac59a9-a6b4-4aed-a26f-d559403c45d2" xlink:to="loc_oust_ShareBasedCompensationArrangementByShareBasedPaymentAwardUnvestedRestrictedStockAwardMember_c7fd6c5d-810c-45af-999a-368bbacdf4b1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_8ed53d84-3497-4065-be6b-a59817b7b22a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_f33db14a-a850-43c3-88d2-c6decbd2cc89" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_8ed53d84-3497-4065-be6b-a59817b7b22a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_a3e3327d-a31f-4531-a6bf-5a355fb2e49a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_a3e3327d-a31f-4531-a6bf-5a355fb2e49a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_a3e3327d-a31f-4531-a6bf-5a355fb2e49a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_a3e3327d-a31f-4531-a6bf-5a355fb2e49a" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_a3e3327d-a31f-4531-a6bf-5a355fb2e49a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_e9c55fd9-84e1-4336-b050-2350cbfc581f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_a3e3327d-a31f-4531-a6bf-5a355fb2e49a" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_e9c55fd9-84e1-4336-b050-2350cbfc581f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_eaebf0e1-185a-456f-a6a6-837c4ad6cba2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_e9c55fd9-84e1-4336-b050-2350cbfc581f" xlink:to="loc_us-gaap_DomesticCountryMember_eaebf0e1-185a-456f-a6a6-837c4ad6cba2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_4601123e-96f9-41f4-89f1-bbc7c81e330b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_e9c55fd9-84e1-4336-b050-2350cbfc581f" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_4601123e-96f9-41f4-89f1-bbc7c81e330b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_1460003d-e38e-46c2-91c6-a80897954921" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_1460003d-e38e-46c2-91c6-a80897954921" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_1460003d-e38e-46c2-91c6-a80897954921_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_1460003d-e38e-46c2-91c6-a80897954921" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_1460003d-e38e-46c2-91c6-a80897954921_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_808a7519-8dc9-4b83-94bb-575f09471e26" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_1460003d-e38e-46c2-91c6-a80897954921" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_808a7519-8dc9-4b83-94bb-575f09471e26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember_05581cc9-f869-4933-b6ac-da14cc64bb64" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InternalRevenueServiceIRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_808a7519-8dc9-4b83-94bb-575f09471e26" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember_05581cc9-f869-4933-b6ac-da14cc64bb64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CaliforniaFranchiseTaxBoardMember_d5b1e17d-3263-44f8-85eb-e0c1b3bd2e27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CaliforniaFranchiseTaxBoardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_808a7519-8dc9-4b83-94bb-575f09471e26" xlink:to="loc_us-gaap_CaliforniaFranchiseTaxBoardMember_d5b1e17d-3263-44f8-85eb-e0c1b3bd2e27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLossCarryforwardsExpirationPeriodsAxis_575b6c57-dda8-4ff6-9e9f-d7eeaae43992" xlink:href="oust-20241231.xsd#oust_OperatingLossCarryforwardsExpirationPeriodsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:to="loc_oust_OperatingLossCarryforwardsExpirationPeriodsAxis_575b6c57-dda8-4ff6-9e9f-d7eeaae43992" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLossCarryforwardsExpirationPeriodsDomain_575b6c57-dda8-4ff6-9e9f-d7eeaae43992_default" xlink:href="oust-20241231.xsd#oust_OperatingLossCarryforwardsExpirationPeriodsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_oust_OperatingLossCarryforwardsExpirationPeriodsAxis_575b6c57-dda8-4ff6-9e9f-d7eeaae43992" xlink:to="loc_oust_OperatingLossCarryforwardsExpirationPeriodsDomain_575b6c57-dda8-4ff6-9e9f-d7eeaae43992_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLossCarryforwardsExpirationPeriodsDomain_d3056c29-1560-4b83-8647-5c0682b17515" xlink:href="oust-20241231.xsd#oust_OperatingLossCarryforwardsExpirationPeriodsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_oust_OperatingLossCarryforwardsExpirationPeriodsAxis_575b6c57-dda8-4ff6-9e9f-d7eeaae43992" xlink:to="loc_oust_OperatingLossCarryforwardsExpirationPeriodsDomain_d3056c29-1560-4b83-8647-5c0682b17515" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OperatingLossCarryforwardsExpirationYearUnlimitedMember_86237dd3-5c8c-4eaa-a708-2821dfbd1c9a" xlink:href="oust-20241231.xsd#oust_OperatingLossCarryforwardsExpirationYearUnlimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oust_OperatingLossCarryforwardsExpirationPeriodsDomain_d3056c29-1560-4b83-8647-5c0682b17515" xlink:to="loc_oust_OperatingLossCarryforwardsExpirationYearUnlimitedMember_86237dd3-5c8c-4eaa-a708-2821dfbd1c9a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_c83daf4f-353d-40bb-9a57-21882290c640" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_6a9ef4eb-7212-459d-a294-cf4dbeafb5fa" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_c83daf4f-353d-40bb-9a57-21882290c640" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_c83daf4f-353d-40bb-9a57-21882290c640_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_c83daf4f-353d-40bb-9a57-21882290c640" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_c83daf4f-353d-40bb-9a57-21882290c640_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_3423727f-3356-401c-abbd-568b7d84d5f0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_c83daf4f-353d-40bb-9a57-21882290c640" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_3423727f-3356-401c-abbd-568b7d84d5f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchMember_46ef7986-13c9-48da-88a2-f2d3c5c6cd40" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_3423727f-3356-401c-abbd-568b7d84d5f0" xlink:to="loc_us-gaap_ResearchMember_46ef7986-13c9-48da-88a2-f2d3c5c6cd40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_3458549c-4d80-4a82-a25a-61b774608c39" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_3458549c-4d80-4a82-a25a-61b774608c39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_e57dd74e-6679-4c65-8daf-b2600cc1dbdb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_e57dd74e-6679-4c65-8daf-b2600cc1dbdb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_b9c5baa9-658f-4c5e-adb1-fb7d3e3a0597" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_OperatingLossCarryforwards_b9c5baa9-658f-4c5e-adb1-fb7d3e3a0597" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_a757f9ae-5827-473e-83f2-ff3829ddb5eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_a757f9ae-5827-473e-83f2-ff3829ddb5eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_8b5bd0e5-1b2d-4019-8124-3cb8aab6f574" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_8b5bd0e5-1b2d-4019-8124-3cb8aab6f574" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_83c3d6c0-7075-4fb2-8521-6f5b6cdd31da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_4a2cd410-a93c-4e68-abb4-359a0dc03f95" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_83c3d6c0-7075-4fb2-8521-6f5b6cdd31da" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_97168c4e-4bab-47e9-b906-b17557563da1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_6e715248-3504-4689-9916-7b9fe5572001" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_97168c4e-4bab-47e9-b906-b17557563da1" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_6e715248-3504-4689-9916-7b9fe5572001" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6e715248-3504-4689-9916-7b9fe5572001" xlink:to="loc_srt_ProductOrServiceAxis_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba" xlink:to="loc_srt_ProductsAndServicesDomain_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5c10dcbd-3c72-4c8d-a154-bc143f6d991a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_db053144-a6b5-4f08-8ee9-4bc9eb7fd8ba" xlink:to="loc_srt_ProductsAndServicesDomain_5c10dcbd-3c72-4c8d-a154-bc143f6d991a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MultiYearLicensingContractsMember_ffc7f89d-2d44-41a2-8585-e1570116d048" xlink:href="oust-20241231.xsd#oust_MultiYearLicensingContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5c10dcbd-3c72-4c8d-a154-bc143f6d991a" xlink:to="loc_oust_MultiYearLicensingContractsMember_ffc7f89d-2d44-41a2-8585-e1570116d048" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_de819ef7-3c5f-4bde-9af9-2c7d47dd478a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6e715248-3504-4689-9916-7b9fe5572001" xlink:to="loc_srt_MajorCustomersAxis_de819ef7-3c5f-4bde-9af9-2c7d47dd478a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_de819ef7-3c5f-4bde-9af9-2c7d47dd478a_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_de819ef7-3c5f-4bde-9af9-2c7d47dd478a" xlink:to="loc_srt_NameOfMajorCustomerDomain_de819ef7-3c5f-4bde-9af9-2c7d47dd478a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_bbf8c4f5-4500-4c46-b4ac-d7f381827de5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_de819ef7-3c5f-4bde-9af9-2c7d47dd478a" xlink:to="loc_srt_NameOfMajorCustomerDomain_bbf8c4f5-4500-4c46-b4ac-d7f381827de5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OneCustomerWithMultiyearContractEnteredIn2023Member_d966d88b-0f49-41b2-9b4f-eaf8553fbf42" xlink:href="oust-20241231.xsd#oust_OneCustomerWithMultiyearContractEnteredIn2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_bbf8c4f5-4500-4c46-b4ac-d7f381827de5" xlink:to="loc_oust_OneCustomerWithMultiyearContractEnteredIn2023Member_d966d88b-0f49-41b2-9b4f-eaf8553fbf42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a5d3d9d5-05b6-48aa-9627-7282e6e4b386" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_97168c4e-4bab-47e9-b906-b17557563da1" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_a5d3d9d5-05b6-48aa-9627-7282e6e4b386" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDepositsFromCustomers_b789eefa-2960-40e5-bcd9-860150cd9823" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromDepositsFromCustomers"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_97168c4e-4bab-47e9-b906-b17557563da1" xlink:to="loc_us-gaap_ProceedsFromDepositsFromCustomers_b789eefa-2960-40e5-bcd9-860150cd9823" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_e4e06629-da65-4d3b-88cb-6afdd167b6df" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_97168c4e-4bab-47e9-b906-b17557563da1" xlink:to="loc_us-gaap_ContractWithCustomerLiability_e4e06629-da65-4d3b-88cb-6afdd167b6df" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#RevenueScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/RevenueScheduleofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_14c7070a-6f1b-4b3c-996c-3cfad0467b99" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_49d33a92-be6e-47ba-a1d0-4e3cf7bbb4fd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_14c7070a-6f1b-4b3c-996c-3cfad0467b99" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_49d33a92-be6e-47ba-a1d0-4e3cf7bbb4fd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_2ca461ac-d62a-4c2c-8448-118b19ac3516" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_49d33a92-be6e-47ba-a1d0-4e3cf7bbb4fd" xlink:to="loc_srt_StatementGeographicalAxis_2ca461ac-d62a-4c2c-8448-118b19ac3516" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_2ca461ac-d62a-4c2c-8448-118b19ac3516_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_2ca461ac-d62a-4c2c-8448-118b19ac3516" xlink:to="loc_srt_SegmentGeographicalDomain_2ca461ac-d62a-4c2c-8448-118b19ac3516_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_b49cab17-8132-493f-8178-1cbf25d0d267" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_2ca461ac-d62a-4c2c-8448-118b19ac3516" xlink:to="loc_srt_SegmentGeographicalDomain_b49cab17-8132-493f-8178-1cbf25d0d267" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AmericasMember_a230e394-e7ef-4631-ad21-30333571f8fd" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AmericasMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b49cab17-8132-493f-8178-1cbf25d0d267" xlink:to="loc_srt_AmericasMember_a230e394-e7ef-4631-ad21-30333571f8fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_430e5249-75fb-4ed2-9ace-f6b77e1c9a8c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b49cab17-8132-493f-8178-1cbf25d0d267" xlink:to="loc_srt_AsiaPacificMember_430e5249-75fb-4ed2-9ace-f6b77e1c9a8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EMEAMember_8519ec7b-6f71-4ea9-8b6c-01af84bbb089" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EMEAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_b49cab17-8132-493f-8178-1cbf25d0d267" xlink:to="loc_us-gaap_EMEAMember_8519ec7b-6f71-4ea9-8b6c-01af84bbb089" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0581070b-32c1-492a-8208-e9044459e9ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_14c7070a-6f1b-4b3c-996c-3cfad0467b99" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0581070b-32c1-492a-8208-e9044459e9ad" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/RevenueSchedulesofConcentrationofRiskDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#RevenueSchedulesofConcentrationofRiskDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/RevenueSchedulesofConcentrationofRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_cff780ef-c795-4aa8-a774-2a6a19295367" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_cff780ef-c795-4aa8-a774-2a6a19295367" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_99b963c8-5977-480f-9f54-89d778409ac7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_99b963c8-5977-480f-9f54-89d778409ac7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_99b963c8-5977-480f-9f54-89d778409ac7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_99b963c8-5977-480f-9f54-89d778409ac7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_99b963c8-5977-480f-9f54-89d778409ac7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_671a141e-5c7c-468e-8f4b-1736b0f31397" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_99b963c8-5977-480f-9f54-89d778409ac7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_671a141e-5c7c-468e-8f4b-1736b0f31397" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_a4751f9f-013a-4ea0-bd02-a91a041f3d37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_671a141e-5c7c-468e-8f4b-1736b0f31397" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_a4751f9f-013a-4ea0-bd02-a91a041f3d37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_c3407e01-ccba-442f-b547-325ccb7f3a31" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_b1fd01a5-eaa6-4528-bfa4-f4b5ce9ddc8a" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_c3407e01-ccba-442f-b547-325ccb7f3a31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_c55e6cef-f750-43d7-b6f7-bfc2709430c6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_c3407e01-ccba-442f-b547-325ccb7f3a31" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_c55e6cef-f750-43d7-b6f7-bfc2709430c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_45107967-44ad-4cd1-a3e5-08f96e633ab8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_c3407e01-ccba-442f-b547-325ccb7f3a31" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_45107967-44ad-4cd1-a3e5-08f96e633ab8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_3e8d15ce-7e03-44df-af50-a62e56db114b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:to="loc_srt_MajorCustomersAxis_3e8d15ce-7e03-44df-af50-a62e56db114b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_3e8d15ce-7e03-44df-af50-a62e56db114b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_3e8d15ce-7e03-44df-af50-a62e56db114b" xlink:to="loc_srt_NameOfMajorCustomerDomain_3e8d15ce-7e03-44df-af50-a62e56db114b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_c97ba1cf-0b44-43cc-91e8-4af43f4fccb0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_3e8d15ce-7e03-44df-af50-a62e56db114b" xlink:to="loc_srt_NameOfMajorCustomerDomain_c97ba1cf-0b44-43cc-91e8-4af43f4fccb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_CustomerEMember_d0060884-c5cf-4996-92dd-89ab6cf2465a" xlink:href="oust-20241231.xsd#oust_CustomerEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_c97ba1cf-0b44-43cc-91e8-4af43f4fccb0" xlink:to="loc_oust_CustomerEMember_d0060884-c5cf-4996-92dd-89ab6cf2465a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_2f9f802d-5677-4515-a40a-8ec9aedbdb28" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_fa32f20e-e592-4911-83b7-31c67273bea7" xlink:to="loc_srt_StatementGeographicalAxis_2f9f802d-5677-4515-a40a-8ec9aedbdb28" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_2f9f802d-5677-4515-a40a-8ec9aedbdb28_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_2f9f802d-5677-4515-a40a-8ec9aedbdb28" xlink:to="loc_srt_SegmentGeographicalDomain_2f9f802d-5677-4515-a40a-8ec9aedbdb28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a9adbc2c-70da-44b2-a460-a180a287748c" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_2f9f802d-5677-4515-a40a-8ec9aedbdb28" xlink:to="loc_srt_SegmentGeographicalDomain_a9adbc2c-70da-44b2-a460-a180a287748c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_8b30e22d-3ecd-46ad-a01f-32360f4905f1" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a9adbc2c-70da-44b2-a460-a180a287748c" xlink:to="loc_country_US_8b30e22d-3ecd-46ad-a01f-32360f4905f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_SE_08823206-ff62-420e-aef5-c44c42f28225" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_SE"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a9adbc2c-70da-44b2-a460-a180a287748c" xlink:to="loc_country_SE_08823206-ff62-420e-aef5-c44c42f28225" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_78101cb6-f1ac-4e6e-9237-50767a27bf68" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_cff780ef-c795-4aa8-a774-2a6a19295367" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_78101cb6-f1ac-4e6e-9237-50767a27bf68" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/RevenueScheduleofContractLiabilitiesDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#RevenueScheduleofContractLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/RevenueScheduleofContractLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_566c80ea-53b2-4425-8399-9ec8e01984cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_a6343f3f-c4c4-4379-b50f-eb7072da087f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_566c80ea-53b2-4425-8399-9ec8e01984cd" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_a6343f3f-c4c4-4379-b50f-eb7072da087f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_16bd058b-8311-47aa-a571-2b855d0202fe" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_a6343f3f-c4c4-4379-b50f-eb7072da087f" xlink:to="loc_srt_ProductOrServiceAxis_16bd058b-8311-47aa-a571-2b855d0202fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_16bd058b-8311-47aa-a571-2b855d0202fe_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_16bd058b-8311-47aa-a571-2b855d0202fe" xlink:to="loc_srt_ProductsAndServicesDomain_16bd058b-8311-47aa-a571-2b855d0202fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c98469bb-6843-402c-a673-1e4254908742" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_16bd058b-8311-47aa-a571-2b855d0202fe" xlink:to="loc_srt_ProductsAndServicesDomain_c98469bb-6843-402c-a673-1e4254908742" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MultiYearLicensingContractsMember_b7a2912e-e6d1-4021-a172-d852f6592ae0" xlink:href="oust-20241231.xsd#oust_MultiYearLicensingContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c98469bb-6843-402c-a673-1e4254908742" xlink:to="loc_oust_MultiYearLicensingContractsMember_b7a2912e-e6d1-4021-a172-d852f6592ae0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_OtherContractsMember_9ecd96c5-2c4b-4012-9a5e-6add3e401be6" xlink:href="oust-20241231.xsd#oust_OtherContractsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_c98469bb-6843-402c-a673-1e4254908742" xlink:to="loc_oust_OtherContractsMember_9ecd96c5-2c4b-4012-9a5e-6add3e401be6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ContractWithCustomerLiabilityCurrentAbstract_e6c53a14-4410-422f-b2b4-ec79dd9764ba" xlink:href="oust-20241231.xsd#oust_ContractWithCustomerLiabilityCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_566c80ea-53b2-4425-8399-9ec8e01984cd" xlink:to="loc_oust_ContractWithCustomerLiabilityCurrentAbstract_e6c53a14-4410-422f-b2b4-ec79dd9764ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_728affe3-7fa9-4189-b2b1-9030e9904277" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oust_ContractWithCustomerLiabilityCurrentAbstract_e6c53a14-4410-422f-b2b4-ec79dd9764ba" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_728affe3-7fa9-4189-b2b1-9030e9904277" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ContractWithCustomerLiabilityNoncurrentAbstract_b824bdba-ce0a-4d01-8c6a-432b7eb4dbda" xlink:href="oust-20241231.xsd#oust_ContractWithCustomerLiabilityNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_566c80ea-53b2-4425-8399-9ec8e01984cd" xlink:to="loc_oust_ContractWithCustomerLiabilityNoncurrentAbstract_b824bdba-ce0a-4d01-8c6a-432b7eb4dbda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_f87dbd6e-536d-4431-98d0-e9fa4ab024f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_oust_ContractWithCustomerLiabilityNoncurrentAbstract_b824bdba-ce0a-4d01-8c6a-432b7eb4dbda" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityNoncurrent_f87dbd6e-536d-4431-98d0-e9fa4ab024f2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_03b3193c-6e68-4fa3-b195-d6f8a26ee815" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_566c80ea-53b2-4425-8399-9ec8e01984cd" xlink:to="loc_us-gaap_ContractWithCustomerLiability_03b3193c-6e68-4fa3-b195-d6f8a26ee815" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://ouster.com/role/SegmentsScheduleofSegmentReportingInformationDetails" xlink:type="simple" xlink:href="oust-20241231.xsd#SegmentsScheduleofSegmentReportingInformationDetails"/>
  <link:definitionLink xlink:role="http://ouster.com/role/SegmentsScheduleofSegmentReportingInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_d432a358-2136-43df-80c5-8ad432536dae" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_af7c3dee-acfa-4485-b3f0-0719b9caf360" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d432a358-2136-43df-80c5-8ad432536dae" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_af7c3dee-acfa-4485-b3f0-0719b9caf360" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_af7c3dee-acfa-4485-b3f0-0719b9caf360" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd" xlink:to="loc_us-gaap_SegmentDomain_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_518bde26-8426-4162-9f4c-03cadf31ebb9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0e2f8be4-c160-4bc7-8b5e-8e2ae24888cd" xlink:to="loc_us-gaap_SegmentDomain_518bde26-8426-4162-9f4c-03cadf31ebb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_ReportableSegmentMember_4c14736c-4804-4f97-9dc1-614e20aeced3" xlink:href="oust-20241231.xsd#oust_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_518bde26-8426-4162-9f4c-03cadf31ebb9" xlink:to="loc_oust_ReportableSegmentMember_4c14736c-4804-4f97-9dc1-614e20aeced3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7b3574e0-31b3-481e-a3c4-9bba3c804664" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d432a358-2136-43df-80c5-8ad432536dae" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7b3574e0-31b3-481e-a3c4-9bba3c804664" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_d432a358-2136-43df-80c5-8ad432536dae" xlink:to="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ManufacturingCosts_fba493ad-5b94-41fe-9291-d3b98a894fe0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ManufacturingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_ManufacturingCosts_fba493ad-5b94-41fe-9291-d3b98a894fe0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_db7bca7f-1c7c-429e-a8ab-49d686ab7ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_ShareBasedCompensation_db7bca7f-1c7c-429e-a8ab-49d686ab7ee9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCostOfOperatingRevenue_0f00d4a6-8914-4b3f-b5ff-2ff7f377fdee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherCostOfOperatingRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_OtherCostOfOperatingRevenue_0f00d4a6-8914-4b3f-b5ff-2ff7f377fdee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_2c28469a-ee9e-402f-a3f9-4e297124a643" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_2c28469a-ee9e-402f-a3f9-4e297124a643" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_2d94dc32-f79b-4600-9077-6a62a4b61c49" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_SellingAndMarketingExpense_2d94dc32-f79b-4600-9077-6a62a4b61c49" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_4ee840ec-23c6-441c-93c6-a3952070b762" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_4ee840ec-23c6-441c-93c6-a3952070b762" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_e03c410a-e9b9-4a47-9648-0bb76339439a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_e03c410a-e9b9-4a47-9648-0bb76339439a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_313f14cc-9a7d-42bf-b51b-a8188e9fac4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_313f14cc-9a7d-42bf-b51b-a8188e9fac4f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_335d0db0-893d-4299-b48f-571154141479" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_335d0db0-893d-4299-b48f-571154141479" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_47e35345-5721-4b3b-b1f3-77058526dde4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_473c8032-1be0-4a74-9a0b-1b8e3b263fb8" xlink:to="loc_us-gaap_NetIncomeLoss_47e35345-5721-4b3b-b1f3-77058526dde4" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_MeganChungMember_16b9fdd5-917b-429b-b302-a97d310a78c6" xlink:href="oust-20241231.xsd#oust_MeganChungMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_oust_MeganChungMember_16b9fdd5-917b-429b-b302-a97d310a78c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_oust_TheodoreTewksburyMember_0bd4fd54-ba71-42b3-b279-ce123b339c67" xlink:href="oust-20241231.xsd#oust_TheodoreTewksburyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_oust_TheodoreTewksburyMember_0bd4fd54-ba71-42b3-b279-ce123b339c67" xlink:type="arc" order="3"/>
  </link:definitionLink>
</link:linkbase>
