Final answer:
The name of the Microsoft repository for information on threats detected by Windows Defender is the Windows Defender Security Intelligence (WDSI).
Step-by-step explanation:
The repository of information about threats that Windows Defender discovers is known as the Windows Defender Security Intelligence (WDSI) repository. This database includes details about different types of malware, viruses, and other potential threats that the Windows Defender antivirus product can detect and protect against. The WDSI repository is an important resource for users and IT professionals to stay informed about the latest cybersecurity threats and how to mitigate them.