(uncountable) That which is perceived as silly or frivolous. / (countable) An act that is silly; a result of being silly.

plural of silliness

Laughable or amusing through foolishness or a foolish appearance. / (of numbers, particularly prices) Absurdly large. / Good; pious. / Holy.

(now regional or colloquial) Sillily: in a silly manner.

(colloquial) A silly person. / (endearing, gently derogatory) A term of address. / (colloquial) A mistake.

plural of silly / (informal, as "the sillies") A period of foolish behaviour.

(informal) A silly person; a simpleton.

(cricket) A fielding position, on the off side, square of the batsman's wicket, and very near the batsman; a fielder in this position.

(cricket) a fielding position, on the leg side, forward of the batsman's wicket, and very near the batsman; a fielder in this position

(idiomatic) A ridiculously large (or, less commonly, small) sum of money.