An unspecified, vaguely disreputable person.
A funny person.
A friendly unit that acts as a suspected hostile unit in a military excercise.
A jester.
A person who makes jokes.
A clause in a contract that undermines its apparent provisions.
A man.
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.
A contemptible person.
A white-bodied, wood-consuming insect of the infraorder Isoptera, in the order Blattodea.
Of a chimpanzee: to catch termites by inserting a stick or vine into their nest and waiting for them to climb up it.