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

Smithson’s biographer, Heather Ewing, has noted that Smithson was friends with a “who’s who of European science,” men who “proclaimed themselves citizens of the globe.”

Read more on The Wall Street Journal

Holmes had a who’s who of prominent men on her board, including former Secretaries of State George Shultz and Henry Kissinger and former Defense Secretaries Jim Mattis and William J. Perry.

Read more on The Wall Street Journal

There are a lot of moving parts in “The Gold,” represented in sometimes brief alternating scenes, and it may take a while, among the crooks, at least, to get a handle on things, to sort out where you are, who’s who, who’s married to whom, and what part each plays in the caper.

Read more on Los Angeles Times

A shelf in their airy studio discreetly catalogs her career highlights: faded photographs with Hillary Clinton and Wood; a copy of the “Who’s Who in American Art” that features Matzkin; a group family photo at the Smithsonian.

Read more on Los Angeles Times

Ringside was a who's who of boxing and entertainment, from legends Mike Tyson, Evander Holyfield, and Thomas Hearns to singer Lizzo and actor Mark Wahlberg.

Read more on BBC