First Known Use: 1541
Dictionary
lunacy
noun lu·na·cy \ˈlü-nə-sē\
: extreme foolishness
: something that is very foolish
: extreme mental illness
plural lu·na·cies
Full Definition of LUNACY
1
a : insanity b : intermittent insanity once believed to be related to phases of the moon
2
: wild foolishness : extravagant folly
3
: a foolish act
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Origin of LUNACY
lunatic
Related to LUNACY
Other Psychology Terms
Medical Dictionary
lunacy
noun lu·na·cy \ˈlü-nə-sē\
plural lu·na·cies
Medical Definition of LUNACY
: insanity; also : intermittent insanity once believed to be related to phases of the moon
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