fool 
(fl)
(fl)n.
1. One who is deficient in judgment, sense, or understanding.
2. One who acts unwisely on a given occasion: I was a fool to have quit my 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.
4. Informal A person with a talent or enthusiasm for a certain activity: a dancing fool; a fool for skiing.
5. A member of a royal or noble household who provided entertainment, as with jokes or antics; a jester.
6. One who subverts convention or orthodoxy or varies from social conformity in order to reveal spiritual or moral truth: a holy fool.
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.
v. fooled, fool·ing, fools
v.tr.
1. To deceive or trick; dupe: "trying to learn how to fool a trout with a little bit of floating fur and feather" (Charles Kuralt).
2. To confound or prove wrong; surprise, especially pleasantly: We were sure they would fail, but they fooled us.
v.intr.
1. Informal
a. To speak or act facetiously or in jest; joke: I was just fooling when I said I had to leave.
b. To behave comically; clown.
c. To feign; pretend: He said he had a toothache but he was only fooling.
2. To engage in idle or frivolous activity.
3. To toy, tinker, or mess: shouldn't fool with matches.
adj.
Informal
Phrasal Verbs: Informal
Foolish; stupid: off on some fool errand or other.
fool around Informal
1. To engage in idle or casual activity; putter: was fooling around with the old car in hopes of fixing it.
2. To engage in frivolous activity; make fun.
3. To engage in casual sexual activity.
4.
a. To have a sexual affair with someone who is not one's spouse or partner.
b. To have many sexual affairs.
fool away
Idiom: To waste (time or money) foolishly; squander: fooled away the week's pay on Friday night.
play/act the fool
1. To act in an irresponsible or foolish manner.
2. To behave in a playful or comical manner.
[Middle English fol, from Old French, from Late Latin follis, windbag, fool, from Latin follis, bellows; see bhel-2 in the Appendix of Indo-European roots.]