have a screw loose

Idioms

Be mentally unstable or eccentric, as in Anyone who approves that purchase must have a screw loose. This term likens a mental weakness to a machine in which a part is not securely fastened. An antonym is have one's head screwed on right; for example, She's very capable; she has her head screwed on right. [Slang; early 1800s]

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

“Everyone in speedskating recognizes that Eric Heiden is the greatest speedskater who ever lived. Even saying, ‘Yeah, we should try that,’ that’s like saying, ‘Do you have a screw loose or something?’

From Washington Times • Mar. 8, 2023

“But you have to have a screw loose to play this position.”

From New York Times • Nov. 24, 2011

Those that think scrapping everything kind of have a screw loose.

From Forbes • Oct. 14, 2011

But one Sebring dictum must be strictly observed: "Oil is for machinery and moving parts; unless you have a screw loose, it has no place on the head."

From Time Magazine Archive

I really and truly believe he must have a screw loose in the upper story.”

From The Big Five Motorcycle Boys on the Battle Line Or, With the Allies in France by Marlow, Ralph

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023