lunacy

[ loo-nuh-see ]
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noun,plural lu·na·cies.
  1. insanity; mental disorder.

  2. intermittent insanity, formerly believed to be related to phases of the moon.

  1. extreme foolishness or an instance of it: Her decision to resign was sheer lunacy.

  2. unsoundness of mind sufficient to incapacitate one for civil transactions: a former legal term.

Origin of lunacy

1
First recorded in 1535–45; lun(atic) + -acy

Other words for lunacy

Opposites for lunacy

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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use lunacy in a sentence

British Dictionary definitions for lunacy

lunacy

/ (ˈluːnəsɪ) /


nounplural -cies
  1. (formerly) any severe mental illness

  2. foolishness or a foolish act

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012