have a screw loose


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]

QUIZZES

LEARN THE SPANISH WORDS FOR THESE COMMON ANIMALS!

Are you learning Spanish? Or do you just have an interest in foreign languages? Either way, this quiz on Spanish words for animals is for you.
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How do you say “cat” 🐈 in Spanish?
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.