To speak negatively of something. / To reply no.

(idiomatic, chiefly imperative) To smile for a photograph by saying the word "cheese" (the vowel of which, when pronounced as is usual in English, forces a somewhat smile-shaped mouth).

(informal) Authority, as backing some statement, injunction, or command.

(idiomatic) Used to suggest an understatement.

(idiomatic) Clearly, obviously.

(literal sense) To wish someone farewell upon their leaving. / (idiomatic) To separate from someone or something.

present participle of nay-say

Negating; denial; the personality trait of contrariness.

(games) A children's game where players must carry out only those commands that are preceded by the utterance "Simon says".

(idiomatic, colloquial) "What did you say?" or "Repeat what you have said." A polite formula used when one has not heard or understood what has been said.