who / hoō/ • pron. 1. [interrog. pron.] what or which person or people: who is that woman? I wonder who that letter was from. 2. [relative pron.] used to introduce a clause giving further information about a person or people previously mentioned: Joan Fontaine plays the mouse who married the playboy. ∎ archaic the person that; whoever: who holds the sea, perforce doth hold the land.PHRASES: as who should say archaic as if to say: he meekly bowed to him, as who should say “Proceed.”who am I (or are you, is he, etc.) to do something what right or authority do I (or you, he, etc.) have to do something: who am I to object?who goes there? see go¹ .

who Doctor Who central character of a long-running British television science fiction series beginning in 1963, played first by William Hartnell and later by others including Tom Baker; the time-travelling Doctor Who is a Time Lord whose survival includes regular changes of physical appearance. He travels in the Tardis (Time And Relative Dimensions In Space) which resembles an old-fashioned London police telephone box.
Who's Who an annual biographical dictionary of contemporary men and women. It was first issued in 1849 but took its present form in 1897, when it incorporated material from another biographical work, Men and Women of the Time; earlier editions of Who's Who had consisted merely of professional lists, etc. The entries are compiled with the assistance of the subjects themselves, and contain some agreeable eccentricities particularly in the section labelled ‘Recreations’.

who what or which person?; used as relative pron. from XIII. ME. hwo (XII–XIII), who (from XIII), hoo (XIII–XV), repr. OE. hwā̌, corr. to OS. hwē, hwie (Du. wie), OHG. (h)wer (G. wer), OSw. ho, ODa. hwa (Da. hvo), Goth. hwas :- Gmc. *χwaz *χwez :- IE. *qos *qes (cf. Skr. ká-), parallel to *qi (cf. L. quis); cf. L. quī who.
Hence whoso XII, whosoever XIII, whosomever XV.

WHO • abbr. World Health Organization.

WHO (USA) White House Office
• World Health Organization