any of the primate mammals, with the exception of human beings and usu the lemurs and tarsiers, esp any of the smaller longer-tailed primates usu living in trees in tropical countries, esp as contrasted with the apes: families Cebidae, Callitrichidae, and Cercopithecidae
informal a mischievous child; a scamp
any of various machines, implements, or vessels, esp the falling weight of a pile driver
Brit, informal the sum of £500
slang a desperate desire for or addiction to drugs
have a monkey on one's back
slang to be addicted to or dependent on drugs
make a monkey of/make a monkey of
to make (somebody) appear ridiculous
not give a monkey's
slang not to care at all
[prob of low German origin; related to Old Spanish mona monkey]