Have a screw loose
Suggest a CorrectionMeaning
Behave or think in a way the speaker considers eccentric, irrational, or mentally unsound. Informal and potentially offensive. It is often used as comic exaggeration about a reckless idea, but applying it to a person can stigmatize mental illness or eccentricity. Regional use: Widespread informal English.
Origin
The phrase is recorded from 1810. It compares a defect in a person's judgment with a machine or structure that does not work properly because a fastening is loose. Early 19th-century examples could refer broadly to something being wrong in a plan, case, or piece of machinery; the now familiar judgment about a person's mind became one established application of that wider metaphor. No particular machine, factory accident, or named speaker is known to have created it.
Research Sources
Variants
- Have a loose screw
- Have got a screw loose
Usage Examples
- Anyone who enters that cave during a flood must have a screw loose.
- The villagers think the clockmaker has a screw loose, but his calculations are exact.
- Saying that a patient has a screw loose replaces useful information with an insult.