cuck·​oo | \ ˈkü-(ˌ)kü How to pronounce cuckoo (audio) , ˈku̇- How to pronounce cuckoo (audio) \
plural cuckoos

Definition of cuckoo

 (Entry 1 of 3)

1 : a largely grayish-brown European bird (Cuculus canorus) that is a parasite given to laying its eggs in the nests of other birds which hatch them and rear the offspring broadly : any of a large family (Cuculidae of the order Cuculiformes) to which this bird belongs
2 : the call of the cuckoo
3 : a silly or slightly crackbrained person


cuckooed; cuckooing; cuckoos

Definition of cuckoo (Entry 2 of 3)

transitive verb

: to repeat monotonously as a cuckoo does its call



Definition of cuckoo (Entry 3 of 3)

1 : of, relating to, or resembling the cuckoo
2 : deficient in sense or intelligence : silly

Illustration of cuckoo

Illustration of cuckoo


cuckoo 1

In the meaning defined above

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Synonyms & Antonyms for cuckoo

Synonyms: Noun

berk [British], booby, charlie (also charley) [British], ding-a-ling, ding-dong, dingbat, dipstick, doofus [slang], featherhead, fool, git [British], goose, half-wit, jackass, lunatic, mooncalf, nincompoop, ninny, ninnyhammer, nit [chiefly British], nitwit, nut, nutcase, simp, simpleton, turkey, yo-yo

Synonyms: Adjective

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

Antonyms: Adjective

balanced, compos mentis, sane, sound, uncrazy

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Examples of cuckoo in a Sentence


one cuckoo at the campground tried to boil soup in a plastic cup didn't want to be among those cuckoos who race around the mall the day before Christmas


a cuckoo woman who wandered around town carefully gathering up useless trash offered a completely cuckoo suggestion for using the defunct strip mall
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Recent Examples on the Web: Noun

Their relationship is believable — cuckoo, but believable. Soren Andersen, The Seattle Times, "‘The Spy Who Dumped Me’: Kate McKinnon makes familiar action comedy something special," 30 July 2018 In it, Vernon tries hard to entertain a new blue avian friend, unaware that Bird is not sentient but rather a wooden cuckoo fallen from a clock. New York Times, "Brief Tales for New Readers and Little Listeners From Philip Stead and More," 29 June 2018 Workers in Silicon Valley and the San Francisco-Oakland area, driven out of the cuckoo housing markets in those communities, have snapped up cheaper properties in Stockton, accepting the bargain of killer commutes. Steve Lopez,, "Stockton's young mayor has bold turnaround plan: Basic income and stipends for potential shooters," 27 May 2018 Here, for example, is the call of the mangrove cuckoo, a small bird found mainly in coastal South Florida forests. Tarpley Hitt, miamiherald, "A lesson from mating birds: The song gets sweeter over time, a Miami scientist finds | Miami Herald," 29 Mar. 2018 Their destination was Zhalong National Nature Reserve, where reed warblers are parasitised by common cuckoos. The Economist, "Thicker eggshells help cuckoos hatch earlier than their nestmates," 18 Jan. 2018 This occurred because referee Richie Powers went farther over the cuckoo's nest than was permissible even in the NBA of those madcap years, calling three technical fouls each on Nets star Bernard King and coach Kevin Loughery. Bill Livingston,, "Cleveland Cavaliers: The wild day that stopped the doom and gloom -- Bill Livingston," 14 Feb. 2018 The actions pertain to such species as the yellow-billed cuckoo and Miami tiger beetle, along with bats, salamanders and fish. Alan Levin,, "Safe Habitats for Rare Bats and Beetles Quietly Stalled by Trump," 7 Oct. 2017 History will look at his behavior, his erratic and childish lying and his flamboyant ignorance of history itself and pronounce the man, like George III, a cuckoo for whom restraint, but not punishment, was necessary. Richard Cohen, The Mercury News, "Cohen: Donald Trump’s team of bobbleheads," 15 May 2017

Recent Examples on the Web: Adjective

In this very cuckoo moment, Double Shot turned sincere, even sad. Darren Franich,, "In praise of the goofy, shocking, endearing Double Shot at Love finale," 28 June 2019 These cuckoo conspiracy theories are symptomatic of a shift in global values from the optimism of the 1990s, when America’s liberal democracy was universally admired, to the current era of fear and anger, when democracy is in retreat. Trudy Rubin,, "Roseanne's other twisted tweet of the week. (The one you didn't already read about) | Trudy Rubin," 1 June 2018 Celebrities and designers are cuckoo for them: Adele performs with one in her pocket, Kim Kardashian West designed her fragrance after their unique forms, and Mary-Kate and Ashley Olsen offered them to guests at The Row’s most recent fashion show. Rachel Waldman, Vogue, "This Model-Turned-Baker Makes Otherworldly Candy Crystals," 6 Apr. 2018 Alva’s just one of many San Antonians who’s downright cuckoo for Funko Pops. René A. Guzman, San Antonio Express-News, "San Antonio one of many cities madly collecting Funko Pop! figures," 6 Apr. 2018 In cases like these, in which subjects are claiming harm from a cuckoo experiment, the system is set up to punish the institution rather than give redress to the subject. Marisa Taylor, Washington Post, "Unregulated Herpes Experiments Expose ‘Black Hole’ Of Accountability," 21 Dec. 2017 Host birds like reed warblers are wise to the possibility of cuckoo parasitism. Cathleen O'grady, Ars Technica, "Cuckoo calls sound like hawks to distract the birds they’re preying on," 8 Sep. 2017 No manual transmission is available, since many of the car’s active-safety systems don’t play nice with the stick, and Audi tossed the last gen’s lightning-quick dual-clutch auto because Americans are cuckoo for pudding-smooth stoplight launches. Car and Driver, "New Cars for 2018: Audi," 10 Oct. 2017 The sun and moon don’t trade off mechanically, as we have been taught by nursery mobiles and cuckoo clocks. Sam Anderson, New York Times, "New Sentences: From ‘Too Much and Not the Mood,’ by Durga Chew-Bose," 7 July 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cuckoo.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of cuckoo


13th century, in the meaning defined at sense 1


1648, in the meaning defined above


1627, in the meaning defined at sense 1

History and Etymology for cuckoo


Middle English cuccu, of imitative origin

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Time Traveler for cuckoo

The first known use of cuckoo was in the 13th century

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More Definitions for cuckoo



English Language Learners Definition of cuckoo

 (Entry 1 of 2)

: a type of bird that lays its eggs in the nests of other birds and that has a call that sounds like its name



English Language Learners Definition of cuckoo (Entry 2 of 2)

informal + old-fashioned
: silly or crazy
: very enthusiastic


cuck·​oo | \ ˈkü-kü How to pronounce cuckoo (audio) , ˈku̇-\
plural cuckoos

Kids Definition of cuckoo

1 : a grayish brown European bird that lays eggs in the nests of other birds which hatch and raise them
2 : the call of the cuckoo

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More from Merriam-Webster on cuckoo

Rhyming Dictionary: Words that rhyme with cuckoo

Thesaurus: All synonyms and antonyms for cuckoo

Spanish Central: Translation of cuckoo

Nglish: Translation of cuckoo for Spanish Speakers Encyclopedia article about cuckoo

Comments on cuckoo

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to complain fretfully

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