idiocy

UK: /ˈɪdiəsi/ US: /ˈɪdiəsi/ ,(id′ē ə sē)

Inflections of 'idiocy' (n): npl: idiocies

WordReference Random House Learner's Dictionary of American English © 2025

id•i•o•cy /ˈɪdiəsi/   n., pl. -cies. 

1. completely senseless or foolish behavior:
   [uncountable] What idiocy is this? A new computer?
   [countable] new idiocies that will lose money.
2. Psychology the state of being an idiot;
   extreme mental deficiency:
   [uncountable] congenital idiocy.

WordReference Random House Unabridged Dictionary of American English © 2025

id•i•o•cy  (id′ē ə sē), n., pl. -cies. 

1. Psychology utterly senseless or foolish behavior;
   a stupid or foolish act, statement, etc.
2. Psychology the state of being an idiot.

• 1520–30; idio(t) + -cy; compare Greek idiōteía uncouthness

Synonyms

• 1. foolishness, inanity, folly.

Collins Concise English Dictionary © HarperCollins Publishers::

idiocy / ˈɪdɪəsɪ/ noun ( -cies)

1. severe learning difficulties
2. foolishness or senselessness; stupidity
3. a foolish act or remark