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

The company said Jimin and Jung Kook would report to the army together.

From Seattle Times • Dec. 10, 2023

I am high in place with Raa Kook, than whom none is higher, not even Abba Taak, who is highest over the priest. 

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