If you share more about the "long story" reason you need this exact version, I might be able to suggest a more specific workaround (e.g., extracting from a system restore point, volume shadow copy, or Windows image backup).
I understand you're looking for a specific older version of the Windows Defender definition update: , definition version 1.55.1119.0 . If you share more about the "long story"
Here's the direct information you need:
Microsoft does not maintain a public archive of every single old definition version (1.55.1119.0 would be from many years ago, likely around 2016–2018). The official download links from Microsoft always provide the latest definitions, not historical ones. extracting from a system restore point