Merriam-Webster's Collegiate® Dictionary, 11th Edition
MONKEY
I. noun (plural monkeys)
Etymology: probably of Low German origin; akin to Moneke, name of an ape, probably of Romance origin; akin to Old Spanish mona monkey
Date: circa 1530
a nonhuman primate mammal with the exception usually of the lemurs and tarsiers,
2. a person resembling a monkey, a ludicrous figure ; dupe , any of various machines, implements, or vessels, a desperate desire for or addiction to drugs,
II. verb (monkeyed; monkeying)
Date: 1859
transitive verb mimic , mock , intransitive verb to act in a grotesque or mischievous manner,
2. fool , trifle , tamper