who's who

noun

1. a reference work containing short biographical entries on the outstanding persons in a country, industry, profession, etc.:

   a who's who in automotive engineering.

2. the outstanding or influential persons in a community, industry, profession, or other group:

   The who's who of racing will be there.

who's who

noun

1. a book or list containing the names and short biographies of famous people

Word History and Origins

Origin of who's who¹

First recorded in 1840–50

Idioms and Phrases

The outstanding or best-known individuals of a group, as in Tonight's concert features a veritable who's who of musicians . This expression comes from the name of a famous reference work, Who's Who , first published in 1849, which contains biographical sketches of famous individuals and is regularly updated. Its name in turn was based on who is who , that is, the identity of each of a number of persons, a phrase dating from the late 1300s. [Early 1900s]

Example Sentences

Figuring out who’s who, how this will work and what we call each other is a long negotiation that commonly never stops.

From Salon

Among the officials who are confirmed to attend her inauguration is a who’s who of the Latin American left, including Brazilian President Luiz Inácio “Lula” da Silva, Colombian President Gustavo Petro, Chilean President Gabriel Boric and Cuban President Miguel Díaz-Canel.

From Los Angeles Times

The following weeks will see a who’s who from the worlds of comedy, music and movies, including host Nate Bargatze on Oct.

From Los Angeles Times

That’s because “Only Murders in the Building” has featured a who’s who of A-list guest stars, including Sting, Tina Fey, Nathan Lane, Shirley MacLaine, Paul Rudd and Meryl Streep — the latter returns this season as Loretta Durkin, a veteran actress on the rise and the love interest to Oliver.

From Los Angeles Times

Vance and a who’s who of congressional conservatives.

From Slate