IMBECILITY
stupidity, betise, folly, foolishness, imbecility
(noun) a stupid mistake
imbecility
(noun) retardation more severe than a moron but not as severe as an idiot
Source: WordNet® 3.1
Noun
imbecility (countable and uncountable, plural imbecilities)
The quality of being imbecile; weakness; feebleness, especially of mind.
Something imbecilic; a stupid action, behaviour, etc.
Source: Wiktionary
Im`be*cil"i*ty, n.; pl. Imbecilities. Etym: [L. imbecillitas: cf. F.
imbécillité.]
Definition: The quality of being imbecile; weakness; feebleness, esp. of
mind.
Cruelty . . . argues not only a depravedness of nature, but also a
meanness of courage and imbecility of mind. Sir W. Temple.
Note: This term is used specifically to denote natural weakness of
the mental faculties, affecting one's power to act reasonably or
intelligently.
Syn.
– Debility; infirmity; weakness; feebleness; impotence. See
Debility.
Source: Webster’s Unabridged Dictionary 1913 Edition