2. A person who acts unwisely on a given occasion: "He was a fool to have quit his job."
3. One who has been tricked or made to appear ridiculous; a dupe: "They made a fool of me by pretending I had won the contest."
4. Informal, a person with a talent or enthusiasm for a certain activity; such as, a singing fool.
5. A member of a royal or noble household who provided entertainment, as with jokes or antics; a jester.
6. Any one who subverts convention or orthodoxy or varies from social conformity in order to reveal spiritual or moral truth.
7. A dessert made of stewed or puréed fruit mixed with cream or custard and served cold.
8. Archaic: A mentally deficient person; an idiot.
From about 1275, from Old French fol, "madman, insane person"; also, an adjective meaning "mad, insane" from Latin follis, "bellows, leather bag", in Vulgar Latin, used with a sense of "a windbag, an empty-headed person".
The pejorative nature of the term fool is strengthened by a knowledge of its etymology. Its source, the Latin word follis, meant “a bag or sack, a large inflated ball, a pair of bellows.” Users of the word in Late Latin, however, saw a resemblance between the bellows or the inflated ball and someone who was what people now call “a windbag” or “an airhead”.
The word, which passed into English by way of French, is first recorded in English in a work written around the beginning of the 13th century (Chaucer's Canterbury Tales) with the sense “a foolish, a stupid", or "an ignorant person.”