lunatic

1 of 2

noun

lu·​na·​tic ˈlü-nə-ˌtik 

plural lunatics

1

dated, now offensive : someone affected with a severely disordered state of mind

2

informal : a person who behaves in a wildly foolish, reckless, or uncontrolled manner

lunatic

2 of 2

adjective

1

a

dated, now offensive : affected with a severely disordered state of mind

b

dated, now offensive : providing care to mentally ill people

a lunatic asylum

2

informal : wildly foolish

a lunatic idea

lunatic behavior

Synonyms

Adjective

• balmy
• barmy [chiefly British]
• bats
• batty
• bedlam
• bonkers
• brainsick
• bughouse [slang]
• certifiable
• crackbrained
• cracked
• crackers
• crackpot
• cranky [dialect]
• crazed
• crazy
• cuckoo
• daffy
• daft
• demented
• deranged
• fruity [slang]
• gaga
• haywire
• insane
• kooky
• kookie
• loco [slang]
• loony
• looney
• loony tunes
• looney tunes
• mad
• maniacal
• maniac
• mental
• meshuga
• meshugge
• meshugah
• meshuggah
• moonstruck
• non compos mentis
• nuts
• nutty
• psycho
• psychotic
• scatty [chiefly British]
• screwy
• unbalanced
• unhinged
• unsound
• wacko
• whacko
• wacky
• whacky
• wud [chiefly Scottish]

Examples of lunatic in a Sentence

Adjective

He hatched a lunatic plot to overthrow the government.

another of his lunatic ideas

Recent Examples on the Web

Adjective

With his shock of spiky hair and adrenaline rushes, Smith turns a corporate villain into a lunatic new-wave frontman. —Charles McNultytheater Critic, Los Angeles Times, 30 Jan. 2023

The first personality is the lunatic, chaotic artist, with no limits. —John Bleasdale, Variety, 8 Dec. 2022

In an idyllic cabin in the woods, a deaf author named Maddie is trying out new recipes, avoiding her ex-boyfriend's phone calls, and trying to combat writer's block, all while a crazed lunatic waits to strike. —K. Thor Jensen, PCMAG, 20 Oct. 2022

One small exchange, one ship sunk for another, would become a lunatic conflagration. —Ian McEwan, The New Yorker, 1 Aug. 2022

There’s no malice involved in lunatic-appeasement, however. —Erik Wemple, Washington Post, 19 July 2022

Meanwhile, mom Linda (John Roberts) cheerleads with lunatic optimism. —Amy Nicholson, Variety, 23 May 2022

Having long since given up on reigning in the enormous lunatic wing of their party, Republican leaders had, particularly after the rise of Donald Trump, began actively catering to it. —Alex Shephard, The New Republic, 20 Apr. 2022

The point of such a response would be to portray the Democrats as the reasonable party upholding moderation and decency in the face of a lunatic assault on the rights and freedoms of the female half of the population. —Damon Linker, The Week, 1 Apr. 2022

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Word History

Etymology

Adjective

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

Noun

14th century, in the meaning defined at sense 1

Adjective

14th century, in the meaning defined at sense 1a

Phrases Containing lunatic

• lunatic fringe

• lunatic fringe

Kids Definition

lunatic

1 of 2 adjective

lu·​na·​tic

ˈlü-nə-ˌtik

1

a

: insane sense 1

—used chiefly in the past

b

: designed for insane persons

lunatic asylum

—used chiefly in the past

2

: wildly foolish

a lunatic idea

lunatic

2 of 2 noun

: an insane person

—used chiefly in the past

Etymology

Noun

Middle English lunatik "a person driven mad by the changes in the moon," derived from Latin lunaticus (same meaning), from earlier luna "moon"

Word Origin

Lunatic now refers to a person who acts in an unreasonable or wild manner. But until the middle of the 19th century, the word lunatic was used for people who were insane some of the time yet had periods of normal behavior. This was a common meaning of the term in courts of law until recent times. The ancient belief was that changes in the moon affected such people. They were thought to be at their worst during a full moon but normal during a new moon. The Latin word for such a person was lunaticus, which was based on the noun luna, meaning "moon." Lunaticus came into Middle English as lunatik. Then it passed into Modern English as lunatic, meaning "one driven mad by the moon."

Medical Definition

lunatic

noun

lu·​na·​tic ˈlü-nə-ˌtik 

dated, now offensive : an individual marked by a severely disordered state of mind

Legal Definition

lunatic

noun

lu·​na·​tic

ˈlü-nə-tik

: an insane person

—used especially formerly

lunatic adjective