lunatic

American  

[loo-nuh-tik] / ˈlu nə tɪk /

noun

• lunatics
  plural

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

Derived Forms

• half-lunatic
  adjective
• lunatically
  adverb

Inflected Forms

Nouns

• lunatics
  plural

Etymology

Origin of lunatic

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

Explanation

A lunatic is someone who is either clinically insane or just acting really crazy. Someone driving too fast and zigging in and out of traffic is driving like a lunatic. The root of this word is luna, which means moon. That's because lunatic originally meant someone who went crazy with every phase of the moon, kind of like a werewolf. Most people these days don't believe in moon-caused insanity, but we still talk about lunatics, sometimes meaning clinically insane people. More often this is a slang term, used mainly in exaggerations, for anyone who seems wild and out of control.

Example Sentences

See Examples For:

lunatic lunatics

Mr. Odenkirk’s warriors make Forrest Gump seem like a ’roid-raging lunatic.

From The Wall Street Journal ● Aug. 13, 2026

"The city is going to bear the scars of this lunatic for a really long time."

From Barron's ● May 15, 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

I’m not an actor, I like working at night, and I’m not going to let you bully me into becoming a Type A lunatic.

From Los Angeles Times ● Nov. 19, 2025

There was an unusual understanding of himself, which was unlike anything I had ever met with in a lunatic; and he took it for granted that his reasons would prevail with others entirely sane.

From "Dracula" by Bram Stoker

Fatboy Slim knew what to expect from the people he was playing to: "They're lunatics," he joked, lovingly.

From BBC ● May 25, 2026

He is the one figure in the story who learns something: How to survive among lunatics.

From The Wall Street Journal ● Apr. 23, 2026

We might not be capable of atrocities, but in our dreams we’re all occasionally raving lunatics, giving vent to feelings we keep buried away in the light of day.

From Los Angeles Times ● Jan. 17, 2026

The “founders and VCs” here are the miners and early buyers who picked up bitcoin at $10, $100, $1,000 — and held on while the rest of us called them lunatics.

From MarketWatch ● Nov. 17, 2025

They seem partly like sheepish schoolboys and partly like lunatics with an hour left to live.

From "All the Light We Cannot See" by Anthony Doerr

Related Words

• crazed
• cuckoo
• maniacal