The definition of a fool is someone with poor judgment.(noun)
An example of a fool is someone who constantly takes dangerous risks.
To fool is defined as to trick or lie to.(verb)
An example of to fool is for a person to trick everyone into believing she is kind and generous when she is really a thief.
See fool in Webster's New World College Dictionary
Origin: ME fol < OFr (Fr fou) < LL follis < L, windbag, bellows: see follicle
Origin: Early ModE < ? fool
See fool in American Heritage Dictionary 4
Origin: Middle English fol
Origin: , from Old French
Origin: , from Late Latin follis, windbag, fool
Origin: , from Latin follis, bellows; see bhel-2 in Indo-European roots. Word History: 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 a person who was what we would 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 with the sense “a foolish, stupid, or ignorant person.”
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