lunacy

From lunatic +‎ -cy.

• (UK) IPA^(key): /ˈluː.nə.si/, /ˈljuː.nə.si/
• (US) IPA^(key): /ˈluː.nə.si/

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lunacy (countable and uncountable, plural lunacies)

1. (of a person or group of people) The state of being mad, insanity
   1. A cyclical mental disease, apparently linked to the lunar phases.
   2. Insanity implying legal irresponsibility.
2. Something deeply misguided.
   • 1867, Fyodor Dostoyevsky, chapter VI, in The Gambler, translated by C. J. Hogarth‎^[1]:

     Two days have passed since that day of lunacy. What a noise and a fuss and a chattering and an uproar there was! And what a welter of unseemliness and disorder and stupidity and bad manners! And I the cause of it all! Yet part of the scene was also ridiculous—at all events to myself it was so.

• (state of being mad): insanity, madness, craziness, craze

• balloonacy
• commission of lunacy