noun

• (derogatory) A person with poor judgment or little intelligence.
  "You were a fool to cross that busy road without looking."
• (historical) A jester; a person whose role was to entertain a sovereign and the court (or lower personages).
  "1896, Frederick Peterson IN Popular Science Monthly Volume 50 December 1896 , Idiots Savants This court fool could say bright things on occasion, but his main use to the ladies and lords of the palace was to serve as victim to practical jokes, cruel, coarse, and vulgar enough to be appreciated perhaps in the Bowery."
• (literature) A stock character typified by unintelligence, naïveté or lucklessness, usually as a form of comic relief; often used as a source of insight or pathos for the audience, as such characters are generally less bound by social expectations.
• (informal) Someone who derives pleasure from something specified.
  "Can they think me […] their fool or jester?"

verb

• (transitive) To trick; to deceive.
  "She bit it gently and found that it resembled a worm in no way whatsoever as to taste although because it was long and slender, a Little Red Hen might easily be fooled by its appearance."
• (intransitive) To act in an idiotic manner; to act foolishly.
  "1681/1682, John Dryden, The Spanish Fryar Is this a time for fooling?"
• (archaic) To make a fool of; to make act the fool.
  "They fool me to the top of my bent."

adj

• (informal) Foolish.
  "Of all the fool, fruitless jobs, making anything of a creature that begins by deceiving her, is the foolest a sane woman ever undertook."

noun

• (cooking) A type of dessert made of puréed fruit and custard or cream.
  "an apricot fool; a gooseberry fool"