Origin and history of *kwo-

"the proper thing" (slang), from Urdu chiz "a thing," from Persian chiz, from Old Persian *ciš-ciy "something," from PIE pronominal root *kwo-. Picked up by British in India by 1818 and used in the sense of "a big thing" (especially in the phrase the real chiz).

This perhaps is behind the expression big cheese "important person" (1914), but that is American English in origin and likely rather belongs to cheese (n.1). To cut a big cheese as a figurative expression for "look important" is recorded from 1915, and overlarge wheels of cheese, especially from Wisconsin, were commonly displayed 19c. as publicity stunts by retailers, etc.

The cheese will be on exhibition at the National Dairy Show at Chicago next week. President Taft will visit the show the morning of Monday, October thirtieth, and after his address he will be invited to cut the big cheese, which will then be distributed in small lots to visitors at the show. [The Country Gentleman, Oct. 28, 1911]

"words spoken at the end of a speech in a play that are the signal for an answering speech," 1550s, of uncertain origin. By one theory it is a spelling out of Q, the letter, which was used 16c., 17c. in stage plays to indicate actors' entrances and was explained at the time as an abbreviation of Latin quando "when" (from PIE root *kwo-, stem of relative and interrogative pronouns) or a similar Latin adverb. Shakespeare's printed texts have it as both Q and cue. Cue as a name for "the letter Q" is attested from 1755.

Transferred to music by 1880. Figurative sense of "sign or hint to speak or act" is from 1560s. The television reader's cue-card is attested by 1948.