Main Entry: lu·na·cy

Pronunciation: \ˈlü-nə-sē\

Function: noun

Inflected Form(s): plural lu·na·cies

Etymology: lunatic

Date: 1541

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