monkey n.

1520s, also monkie, munkie, munkye, etc., not found in Middle English (where ape was the usual word); of uncertain origin, but likely from an unrecorded Middle Low German *moneke or Middle Dutch *monnekijn, a colloquial word for "monkey," originally a diminutive of some Romanic word, compare French monne (16c.); Middle Italian monnicchio, from Old Italian monna; Spanish mona "ape, monkey." In a 1498 Low German version of the popular medieval beast story Roman de Renart ("Reynard the Fox"), Moneke is the name given to the son of Martin the Ape; transmission of the word to English might have been via itinerant entertainers from the German states.

The Old French form of the name is Monequin (recorded as Monnekin in a 14c. version from Hainault), which could be a diminutive of some personal name, or it could be from the general Romanic word, which may be ultimately from Arabic maimun "monkey," literally "auspicious," a euphemistic usage because the sight of apes was held by the Arabs to be unlucky [Klein]. The word would have been influenced in Italian by folk etymology from monna "woman," a contraction of ma donna "my lady."

In general, any one of the primates except man and lemurs; in more restricted use, "an anthropoid ape or baboon;" but popularly used especially of the long-tailed species often kept as pets. Monkey has been used affectionately or in pretended disapproval of a child since c. 1600. As the name of a type of modern popular dance, it is attested from 1964.

Monkey suit is from 1876 as a type of child's suit; by 1918 as slang for "fancy dress clothes or uniform." To make a monkey of "make a fool of" is attested from 1851. To have a monkey on one's back "be addicted" is 1930s narcotics slang, though the same phrase in the 1860s meant "to be angry." There is a story in the Sinbad cycle about a tormenting ape-like creature that mounts a man's shoulders and won't get off, which may be the root of the term. In 1890s British slang, to have a monkey up the chimney meant "to have a mortgage on one's house." The Japanese three wise monkeys ("see no evil," etc.) are attested in English by 1891.

1859, "to mock, mimic" (as a monkey does), from monkey (n.). Meaning "play foolish tricks" is from 1881. To monkey (with) "act in an idle or meddlesome manner" is by 1884. Related: Monkeyed; monkeying.