kook

American  

[kook] / kuk /

noun

Slang.

1. an eccentric, strange, or foolish person.

2. an insane person.

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kook British  

/ kuːk /

noun

1. informal an eccentric, crazy, or foolish person

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Etymology

Origin of kook

First recorded in 1955–60; perhaps alteration of cuckoo

Explanation

A kook is a nut or a weirdo — in other words, an eccentric person. Your favorite aunt might be a bit of a kook, with her crazy hair and wild outfits. The class clown in school is often a kook, saying nutty things in order to get attention, and you may think of the guy in your town who always holds a sign saying, "THE END IS NEAR" as a kook too. The word comes from kooky, "strange," probably stemming from cuckoo, which is a type of bird but also slang for "mad or insane person."

Example Sentences

BTS – comprising members RM, Jin, Saga, J-Hope, Jimin, V and Jung Kook – took a collective hiatus in 2022 for each of them to participate in South Korean mandatory military service.

From Salon • Mar. 27, 2026

The announcement came in a livestream on the Weverse platform in which the group’s seven members — Jin, Suga, J-Hope, RM, Jimin, V and Jung Kook — appeared together for the first time since 2022.

From Los Angeles Times • Jul. 1, 2025

Federal prosecutors are seeking to secure a conviction in a major stock market manipulation case in which Mr. Hwang, whose legal name is Sung Kook Hwang, was one of the big financial losers.

From New York Times • May 8, 2024

On Tuesday, lead vocalist Jung Kook joined the rest of his K-pop band members and enlisted for military service - a requirement of all able-bodied South Korean men aged 18-28.

From BBC • Dec. 12, 2023

There are numerous islands in the group, over all of which Raa Kook is king, although the cluster of islands to the south is restive and occasionally in revolt. 

From The Jacket (Star-Rover) by London, Jack