A fictional villain of DC Comics, noted for his insanity and cunning, who either wears clown makeup or is disfigured to appear as such, and who is archenemy of Batman.

A person who makes jokes.

(slang) A funny person.

A jester.

A playing card that features a picture of a joker (that is, a jester) and that may be used as a wild card in some card games.

An unspecified, vaguely disreputable person or a loser.

(New Zealand, colloquial) A man.

A clause in a contract that undermines its apparent provisions.

(military) A friendly unit that acts as a suspected hostile unit in a military excercise.