who's who

noun

1. (sometimes capitalized) A publication containing biographies of well-known or important people.

2. A list of notable, famous, or upper-class people.

3. Collectively, the elite class.

4. A person appearing in a Who's Who publication.

5. A celebrity or famous person, someone likely to be in such a publication.

6. The identities of specific people, understood in terms of such distinguishing characteristics as their backgrounds, prominence, achievements, jobs, etc., as a basis for comparing them and especially as a basis for ranking them within a social group.