Activity that is mischievous, stupid, or time-wasting. / Activity that is morally questionable or even mildly illegal.

(dated) A type of close-fitting jacket worn by sailors. / A semiformal lightweight jacket, usually made of nylon, with striped cuffs and neck, similar to an MA-1 flight jacket.

(slang, medicine) A new medical student, beginning his/her clinical rotations (often after the first two years of a four-year medical program), or a new resident who is rotating off-service.

(medicine) A viral disease, of primates and some other mammals, related to smallpox, caused by the Monkeypox virus.

(games) A children's game in which two players keep an object away from a third player (who is in between them) by throwing it past that player.

plural of monkey's fist

(literally) A cage containing a banana with a hole large enough for a monkey's hand to fit in, but not large enough for a monkey's fist (clutching a banana) to come out; anecdotally used to catch monkeys that lack the intellect to let go of the banana and run away.

(intransitive, informal) To meddle; to mess (with). / (transitive) To mimic; to ape.

Any member of the clade Simiiformes not also of the clade Hominoidea containing humans and apes, from which they are usually, but not universally, distinguished by smaller size, a tail, and cheek pouches.

plural of Monkey Hanger