I was trying to think of better terminology. Perhaps this works:

Two services can have a common dependency, which still leaves them uncoupled. An example would be a JSON schema validation and serialization/deserialization library. One service can in general bump its dependency version without the other caring, because it'll still send and consume valid JSON.

Two services can have a shared dependency, which couples them. If one service needs to bump its version the other must also bump its version, and in general deployment must ensure they are deployed together so only one version of the shared dependency is live, so to speak. An example could be a library containing business logic.

If you had two independent microservices and added a shared library as per my definition above, you've turned them into a distributed monolith.

Sometimes a common dependency might force a shared deployment, for example a security bug in the JSON library. However that is an exception, and unlike the business logic library. In the shared library case the exception is that one could be bumped without the other caring.