Microsoft provides official executable files containing the latest "Security Intelligence" (definition) updates. You must choose the version that matches your system's architecture (32-bit, 64-bit, or ARM64).
Microsoft Defender Antivirus (formerly Windows Defender) typically updates itself automatically through Windows Update. However, in environments with restricted internet access, air-gapped systems, or when the automatic update service fails, you must perform a . Where to Download Offline Updates windows defender antivirus offline update download
Microsoft Security Intelligence Updates