Definition of imbecile

< imbalance

imbecility >

im·be·cile    (mb-sl, -sl) KEY 

NOUN:

1. A stupid or silly person; a dolt.
2. A person whose mental acumen is well below par.
3. A person of moderate to severe mental retardation having a mental age of from three to seven years and generally being capable of some degree of communication and performance of simple tasks under supervision. The term belongs to a classification system no longer in use and is now considered offensive.

ADJECTIVE:
also im·be·cil·ic  (mb-slk) KEY 

1. Stupid; silly.
2. Well below par in mental acumen.

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ETYMOLOGY:
From obsolete French imbécille, weak, feeble, from Old French, from Latin imbcillus : in-, not ; see in-¹ + possibly bacillum, staff, diminutive of baculum, rod; see bak- in Indo-European roots

OTHER FORMS:
imbe·cile·ly(Adverb)