lu·na·tic \ˈlü-nə-ˌtik\

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SINCE 1828

adjective lu·na·tic \ˈlü-nə-ˌtik\


Definition of lunatic

1
dated a : affected with a severely disordered state of mind : insaneb : designed for the care of mentally ill people a lunatic asylum

2
: wildly foolish a lunatic idea lunatic behavior

lunatic noun

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Examples of lunatic in a sentence

He hatched a lunatic plot to overthrow the government.

another of his lunatic ideas

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Origin and Etymology of lunatic

Middle English lunatik, from Anglo-French or Late Latin; Anglo-French lunatic, from Late Latin lunaticus, from Latin luna; from the belief that lunacy fluctuated with the phases of the moon


First Known Use: 14th century