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ankle jerk

American

noun

a reflex extension of the foot, caused by contraction of the muscles of the calf, resulting from a sharp tap on the Achilles tendon.

Etymology

Origin of ankle jerk

First recorded in 1885–90

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

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.