monkey

Concise Oxford English Dictionary © 2008 Oxford University Press:
monkey/ˈmʌŋki/

▶noun (pl. monkeys)

• 1 a small to medium-sized primate typically having a long tail and living in trees in tropical countries. [Families Cebidae and Callitrichidae (New World), and Cercopithecidae (Old World).]

• 2 a mischievous person, especially a child.

• 3 Brit. informal a sum of £500.

• 4 (also monkey engine) a piledriving machine consisting of a heavy hammer or ram working vertically in a groove.

▶verb (monkeys, monkeying, monkeyed)

• 1 (monkey about/around) behave in a silly or playful way.

  ■ (monkey with) tamper with.

• 2 archaic ape; mimic.

– phrases
make a monkey of (or out of) make (someone) appear ridiculous.
a monkey on one's back informal a burdensome problem.
not give a monkey's Brit. informal not care at all.

– derivatives
monkeyish adjective.

– origin C16: of unknown origin, perh. from Low Ger.