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

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

From Barron's • Mar. 1, 2026

That Tomás, who has already survived the Great Hunger as well as a cruel workhouse, isn’t already a lunatic is perhaps less fantastical than the plot itself at times.

From Los Angeles Times • Jan. 30, 2026

The Macfadyen performance is not of a raving lunatic.

From The Wall Street Journal • Nov. 6, 2025

Act Three, which brings a performance of “Nothing On” to utter collapse, doesn’t quite reach the lunatic heights that Frayn intends.

From Los Angeles Times • Feb. 10, 2025

If he had lived now he might even have been locked in a lunatic hospital, and his friends would certainly have urged him to be psycho-analysed.

From "The Once and Future King" by T. H. White

Related Words

• crazed
• cuckoo
• maniacal