lunatic

American  

[loo-nuh-tik] / ˈlu nə tɪk /

noun

1. (no longer in technical use; now considered offensive) an insane person.

2. a person whose actions and manner are marked by extreme eccentricity or recklessness.

3. a person legally declared to be of unsound mind and who therefore is not held capable or responsible before the law: a former legal term.

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adjective

1. (no longer in technical use; now considered offensive) insane.

2. characteristic or suggestive of lunacy; wildly or recklessly foolish.

3. Older Use. designated for or used by the insane.

   a lunatic asylum.

4. gaily or lightheartedly mad, frivolous, eccentric, etc..

   She has a lunatic charm that is quite engaging.

lunatic British  

/ ˈluːnətɪk /

adjective

1. an archaic word for insane

2. foolish; eccentric; crazy

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noun

1. a person who is insane

Other Word Forms

• half-lunatic adjective
• lunatically adverb

Etymology

Origin of lunatic

1250–1300; Middle English lunatik, from Old French lunatique, from Late Latin lūnāticus “moonstruck.” See Luna, -tic ( def. )

Example Sentences

He got back everything he’s wanted and then a lunatic billionaire is telling you that 100 miles away under the Denver Airport there’s this thing that sounds crazy.

From Los Angeles Times • Mar. 30, 2026

He looked at me like I was a lunatic, but he heard me, so perhaps I planted a seed.

From The Wall Street Journal • Mar. 29, 2026

That is a deliberate choice, says Tracy, because Teddy is not -- or at least not just -- a lunatic.

From Barron's • Mar. 1, 2026

"I'm not a lunatic," Bellamy said after topping Wales' Nations League group last year.

From BBC • Oct. 6, 2025

That horrid thing has the wolves and the rats and his own kind to help him, so I suppose he isn’t above trying to use a respectable lunatic.

From "Dracula" by Bram Stoker

Related Words

• crazed
• cuckoo
• maniacal