lunatic
adjective
lu·na·tic ˈlü-nə-ˌtik 
1
dated
a
: affected with a severely disordered state of mind : insane
b
: designed for the care of mentally ill people
a lunatic asylum
2
: wildly foolish
a lunatic idea
lunatic behavior
lunatic noun
Synonyms
- 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]
See all Synonyms & Antonyms 
Example Sentences
He hatched a lunatic plot to overthrow the government. another of his lunatic ideas
Recent Examples on the Web 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 After the trial, Tyler was sent to lunatic asylum [sic] receiving psychological treatment. Patrick Frater, Variety, 7 Feb. 2022 After the trial, Tyler was sent to lunatic asylum [sic] receiving psychological treatment. Patrick Frater, Variety, 7 Feb. 2022 Marjorie Taylor Greene, the lunatic Georgia MAGA congressman who only recently stopped loving QAnon and thinks that Jewish space lasers might be starting wildfires out west, is one of the right’s biggest stars. Alex Shephard, The New Republic, 28 Feb. 2022 See More
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 After the trial, Tyler was sent to lunatic asylum [sic] receiving psychological treatment. Patrick Frater, Variety, 7 Feb. 2022 After the trial, Tyler was sent to lunatic asylum [sic] receiving psychological treatment. Patrick Frater, Variety, 7 Feb. 2022 Marjorie Taylor Greene, the lunatic Georgia MAGA congressman who only recently stopped loving QAnon and thinks that Jewish space lasers might be starting wildfires out west, is one of the right’s biggest stars. Alex Shephard, The New Republic, 28 Feb. 2022 See More Word History
Etymology
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
14th century, in the meaning defined at sense 1a
Phrases Containing lunatic
Kids Definition
lunatic 1 of 2
adjective
lu·na·tic ˈlü-nə-ˌtik
: insane sense 1
lunatic
2 of 2noun
1
: an insane person
2
: a person who behaves very foolishly
That lunatic went through a red light.
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 1 of 2
adjective
1
as in psychotic
having or showing a very abnormal or sick state of mind he had a lunatic obsession with personal hygiene Synonyms & Similar Words
Relevance
- psychotic
- insane
- mad
- maniac
- nuts
- maniacal
- crazy
- mental
- psycho
- gaga
- paranoid
- crazed
- deranged
- wacko
- loony
- demented
- unhinged
- disturbed
- cuckoo
- bonkers
- looney
- crackpot
- nutty
- irrational
- whacko
- certifiable
- bedlam
- strange
- daft
- eccentric
- batty
- ballistic
- moonstruck
- cracked
- wacky
- kooky
- paranoidal
- daffy
- unbalanced
- crackers
- barmy
- loco
- whacky
- around the bend
- haywire
- screwy
- bats
- foolish
- bughouse
- obsessed
- scatty
- brainsick
- depressed
- odd
- kookie
- meshuga
- unreasonable
- loony tunes
- unsound
- crackbrained
- distraught
- hysterical
- meshuggah
- fey
- delusional
- schizophrenic
- paranoiac
- out to lunch
- neurotic
- fruity
- looney tunes
- cranky
- delusionary
- meshugah
- frantic
- sociopathic
- schizoid
- off
- hysteric
- loopy
- meshugge
- distracted
- queer
- delirious
- wud
- balmy
- nuclear
- oddball
- out of one's mind
- dotty
- touched
- non compos mentis
- off one's rocker
- off one's gourd
- disordered
- raving
- aberrant
- paranoic
- off one's head
- out of one's head
- witless
- tetched
- berserk
- bananas
- obsessive-compulsive
- ape
- monomaniac
- potty
- pixilated
- monomaniacal
- amok
- teched
- senseless
- pixillated
- frenzied
- fixated
- amuck
- wigged-out
Antonyms & Near Antonyms
- sane
- sound
- reasonable
- rational
- balanced
- clear
- sensible
- normal
- compos mentis
- lucid
- wise
- uncrazy
- judicious
- healthy
- well-adjusted
- unneurotic
2
as in stupid
showing or marked by a lack of good sense or judgment such lunatic clowning during a solemn ceremony is completely inappropriate Synonyms & Similar Words
- stupid
- mad
- crazy
- foolish
- silly
- absurd
- insane
- idiotic
- loony
- irrational
- fool
- looney
- crackpot
- ridiculous
- zany
- nutty
- nonsensical
- daft
- dumb
- wacky
- kooky
- cuckoo
- fatuous
- screwball
- witless
- asinine
- idiotical
- daffy
- tomfool
- unreasonable
- dotty
- preposterous
- dippy
- simpleminded
- weak
- harebrained
- simple
- senseless
- brainless
- whacky
- imbecile
- inept
- unwise
- unreasoning
- jerky
- moronic
- kookie
- half-witted
- sappy
- slow
- cockeyed
- half-baked
- lunkheaded
- bubbleheaded
- weak-minded
- feebleminded
- thoughtless
- clueless
- balmy
- illogical
- unreasoned
- lamebrain
- dopey
- doltish
- unintelligent
- pinheaded
- ludicrous
- mindless
- obtuse
- out to lunch
- vacuous
- featherheaded
- thickheaded
- gormless
- oafish
- dunderheaded
- airheaded
- softheaded
- dorky
- farcical
- dull
- imbecilic
- invalid
- laughable
- knuckleheaded
- dim
- surd
- nonrational
- fallacious
- chuckleheaded
- dense
- clownish
- opaque
- brain-dead
- dim-witted
- empty-headed
- lamebrained
- thick
- unsound
- buffoonish
- soft
- notional
- birdbrained
- dopy
- slow-witted
- boobish
- chowderheaded
- unconsidered
- ill-advised
Antonyms & Near Antonyms
- sane
- sensible
- sound
- wise
- prudent
- sage
- sagacious
- reasonable
- judicious
- intelligent
- rational
- clever
- logical
- smart
- bright
- sapient
- valid
- brainy
- well-advised
lunatic
2 of 2noun
1
as in psychopath
a person having or showing a severely disordered or abnormal state of mind he was raving like a lunatic Synonyms & Similar Words
- psychopath
- maniac
- fool
- psycho
- loony
- crazy
- wacko
- nutcase
- schizo
- bug
- loon
- nutter
- psychotic
- sicko
- whacko
- madman
- fruitcake
- nut
- paranoid
- madwoman
- abnormal
- sickie
- patient
- head case
- obsessive
- schizophrenic
- crackbrain
- neurotic
- monomaniac
- schizoid
- character
- deviant
- sociopath
- eccentric
- crack
- weirdo
- kook
- crackpot
- psychoneurotic
- oddball
- fantastic
- zany
- manic-depressive
- screwball
- original
- case
- mythomaniac
- obsessive-compulsive
- codger
- flake
- crank
- schizophrene
- oddity
- tyke
- quiz
- tike
2
as in fool
a person who lacks good sense or judgment no, you can't ski off the roof, you lunatic! Synonyms & Similar Words
- fool
- idiot
- goose
- moron
- nut
- nutcase
- cuckoo
- ninny
- simpleton
- jackass
- monkey
- dingbat
- doofus
- loser
- turkey
- nitwit
- booby
- simp
- charlie
- madman
- daredevil
- nincompoop
- berk
- half-wit
- mooncalf
- dipstick
- git
- featherhead
- imbecile
- dummy
- donkey
- madwoman
- nit
- ninnyhammer
- charley
- ding-a-ling
- ignoramus
- dolt
- ding-dong
- knucklehead
- yo-yo
- goon
- dunce
- blockhead
- weirdo
- kook
- pinhead
- character
- airhead
- crackpot
- numbskull
- scatterbrain
- numskull
- dork
- dope
- schnook
- know-nothing
- schlub
- oddball
- gander
- schlump
- fathead
- screwball
- chump
- laughingstock
- dodo
- crank
- schlemiel
- birdbrain
- stock
- dupe
- shlub
- mockery
- codger
- dumbbell
- butt
- featherbrain
- shlemiel
- crackbrain
Antonyms & Near Antonyms
- genius
- thinker
- brain
- sage
- back-paint
- back-palm
- back-pass
- back-passes
- back-patting
- back-putty
- back-rake
- back-reef
- back-room
- back-scratching
- back-set bed
- back-strapped
- back-tan
- back-tanning
- back-titrate
- back-titration
- back-to-back
- back-to-backs
- back-to-work
- back/paint oneself into a corner
- backache
- backache brake
- backaches
- backaching
- backassward