- Any of various long-tailed, medium-sized members of the order Primates, including the macaques, baboons, guenons, capuchins, marmosets, and tamarins and excluding the anthropoid apes and the prosimians.
- One who behaves in a way suggestive of a monkey, as a mischievous child or a mimic.
- The iron block of a pile driver.
- Slang A person who is mocked, duped, or made to appear a fool: They made a monkey out of him.
- Slang Drug addiction: have a monkey on one's back.
- Informal To play, fiddle, trifle, or tamper with something.
- Informal To behave in a mischievous or apish manner: Stop monkeying around!
- To imitate or mimic; ape.