who's who

noun, often capitalized both Ws
\ ˌhüz-ˈhü How to pronounce who's who (audio) \

Definition of who's who

1 : a compilation of brief biographical sketches of prominent persons in a particular field a who's who of sports figures
2 : the leaders of a group : elite
3 : a listing or grouping of notable persons or things

First Known Use of who's who

1917, in the meaning defined at sense 1

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