lunatic

1 of 2

noun

lu·​na·​tic ˈlü-nə-ˌtik How to pronounce lunatic (audio)
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

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 See all Example Sentences for lunatic 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'lunatic.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

Noun

Middle English lunatik, borrowed from Anglo-French lunatic, borrowed from Late Latin lūnāticus, noun derivative of Latin lūnāticus "suffering from a mental or neurological disorder allegedly affected by the phases of the moon" — more at lunatic entry 2

Adjective

Middle English lunatik "suffering from a recurrent mental or neurological disorder," borrowed from Anglo-French lunatic, borrowed from Latin lūnāticus "suffering from a mental or neurological disorder allegedly affected by the phases of the moon," from lūna "moon" + -āticus, adjective suffix of appurtenance — more at lunar, -age

Note: The word is unattested in classical Latin aside from the legal treatises of Julius Paulus (2nd-3rd centuries a.d.). The derivation was perhaps modeled on fānāticus "inspired by orgiastic rites, fanatic entry 2." Compare Greek (New Testament) selēniázesthai, taken to mean "to suffer from seizures," a derivative of selḗnē "moon."

First Known Use

Noun

14th century, in the meaning defined at sense 1

Adjective

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

Time Traveler
The first known use of lunatic was in the 14th century

Dictionary Entries Near lunatic

Cite this Entry

“Lunatic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lunatic. Accessed 31 Oct. 2024.

Kids Definition

lunatic

1 of 2 adjective
lu·​na·​tic
ˈlü-nə-ˌtik
1
a
: mentally unsound
used chiefly in the past
b
: designed for the care of mentally ill people
lunatic asylum
used chiefly in the past
2
: wildly foolish
a lunatic idea

lunatic

2 of 2 noun
: a mentally ill person
used chiefly in the past

Medical Definition

lunatic

noun
lu·​na·​tic ˈlü-nə-ˌtik How to pronounce lunatic (audio)
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

More from Merriam-Webster on lunatic

Last Updated: - Definition revised
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