A whistle, of two notes, to signify sexual interest in someone.

To whistle in appreciation or sexual interest.

(sports) The blow of the whistle by the referee or other adjudicator signifying the end of the match.

(music) A small, high-pitched metal whistle with six holes that is blown using a fipple.

plural of penny whistle

plural of tin whistle

(idiomatic) To have a drink; to quench one's thirst.

plural of whistleblower

plural of whistler

(colloquial) To make a show of bravery despite one's fears; to put on a brave face. / (idiomatic, US) To speak of something despite having little knowledge of it.