definitions

knee-jerk

[ nee-jurk ]
/ ˈniˌdʒɜrk /
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SEE MORE SYNONYMS FOR knee-jerk ON THESAURUS.COM

adjective

of or relating to a knee-jerk.
Informal. reacting according to a certain habitual manner; unthinking: a knee-jerk liberal.

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RELATED WORDS

expected, predictable, reflex, spontaneous

Nearby words

knee-chest position, knee-deep, knee-elbow position, knee-high, knee-high to a grasshopper, knee-jerk, knee-jerk reflex, knee-length, knee-slapper, knee-socks, knee-sprung

Origin of knee-jerk

First recorded in 1895–1900

Definition for knee-jerk (2 of 2)

knee jerk

noun

a reflex extension of the leg, caused by contraction of the quadriceps, resulting from a sharp tap on the patellar tendon; patellar reflex.

Origin of knee jerk

First recorded in 1875–80
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for knee-jerk

British Dictionary definitions for knee-jerk

knee jerk

noun

Also called: patellar reflex physiol an outward reflex kick of the lower leg caused by a sharp tap on the quadriceps tendon just below the patella

adjective kneejerk

made or occurring as a predictable and automatic response, without thoughtkneejerk support
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for knee-jerk

knee-jerk

n.

patellar reflex, neurological phenomenon discovered and named 1876; the figurative use appeared soon after the phrase was coined.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for knee-jerk

knee jerk

n.

patellar reflex
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.