cuckoo

American  

[koo-koo, kook-oo] / ˈku ku, ˈkʊk u /

noun

plural

cuckoos

1. a common European bird, Cuculus canorus, of the family Cuculidae, noted for its characteristic call and its brood parasitism.

2. any of several other birds of the family Cuculidae.

3. the call of the cuckoo, or an imitation of it.

4. Slang. a crazy, silly, or foolish person; simpleton.

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verb (used without object)

cuckooed, cuckooing

1. to utter the call of the cuckoo or an imitation of it.

verb (used with object)

cuckooed, cuckooing

1. to repeat monotonously.

adjective

1. Slang. crazy; silly; foolish.

2. of, relating to, or like a cuckoo.

cuckoo British  

/ ˈkʊkuː /

noun

1. any bird of the family Cuculidae, having pointed wings, a long tail, and zygodactyl feet: order Cuculiformes. Many species, including the European cuckoo ( Cuculus canorus ), lay their eggs in the nests of other birds and have a two-note call

2. informal an insane or foolish person

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adjective

1. informal insane or foolish

interjection

1. an imitation or representation of the call of a cuckoo

verb

1. (tr) to repeat over and over

2. (intr) to make the sound imitated by the word cuckoo

cuckoo Idioms  

1. see cloud-cuckoo land.

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Etymology

Origin of cuckoo

1200–50; Middle English cuc ( c ) u, cuccuk ( e ) (imitative); compare Latin cucūlus, French coucou, German Kuckuk, Dutch koekoek, Modern Greek koûko

Explanation

A cuckoo is a type of long-tailed bird that's known for laying its eggs in the nests of other birds. In the summer, you're most likely to see cuckoos in various parts of Europe. The famous German cuckoo clock is named for the cuckoo bird, and the cuckoo sound the clock makes each hour imitates the call of the cuckoo. To make this call is also to cuckoo. Informally, you might refer to eccentric or crazy people or situations as cuckoo. Though this informal meaning is credited to American English, the word has been used to mean "stupid person" since at least the 1580s.

Example Sentences

"Switzerland has nurtured many unexpected good things -- Albert Einstein's physics, the world economy, and the cuckoo clock leap to mind -- and is again helping the world appreciate improbable people and ideas."

From Barron's • Mar. 10, 2026

The cuckoo is a parasitic bird that deposits its eggs in the nests of other birds, who then raise its hatchlings with their own.

From The Wall Street Journal • Dec. 4, 2025

Nothing about “Another Simple Favor” or its equally cuckoo bananas predecessor, “A Simple Favor,” is subtle.

From Salon • May 3, 2025

A hand-carved cuckoo clock adds a bit of humor.

From Los Angeles Times • Apr. 17, 2025

Among the trees the wood pigeons called drowsily and from time to time a late cuckoo stammered.

From "Watership Down: A Novel" by Richard Adams