follow Dictionary.com

Why is the ninth month called September?

knee jerk

noun
1.
a reflex extension of the leg, caused by contraction of the quadriceps, resulting from a sharp tap on the patellar tendon; patellar reflex.
Origin
1875-1880
1875-80

knee-jerk

[nee-jurk] /ˈniˌdʒɜrk/
adjective
1.
of or pertaining to a knee-jerk.
2.
Informal. reacting according to a certain habitual manner; unthinking:
a knee-jerk liberal.
Origin
1895-1900
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source
British Dictionary definitions for knee-jerk

knee jerk

noun
1.
(physiol) Also called patellar reflex. an outward reflex kick of the lower leg caused by a sharp tap on the quadriceps tendon just below the patella
modifier
2.
made or occurring as a predictable and automatic response, without thought kneejerk 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
Cite This Source
Word Origin and History for 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
Cite This Source
knee-jerk in Medicine

knee jerk n.
See patellar reflex.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
Slang definitions & phrases for knee-jerk

knee-jerk

modifier

: one more gesture to the knee-jerk hawks in the Congress/ Yet McDonald is no mere knee-jerk critic of the evangelicals

noun
  1. A reflexlike action or response: Being nasty to women is a knee-jerk with him (1958+)
  2. A person who reacts with a reflexlike response: a seventy-year old knee-jerk best remembered for castigating the Reverend Bill Moyers for dancing the frug in the White House (1958+)
verb

: We need less kneejerking on both sides in these arguments about the environment (1980s+)

[fr the patellar reflex, described as knee jerk by 1876]


The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
Cite This Source

Word of the Day

Difficulty index for knee jerk

Few English speakers likely know this word

Word Value for knee

8
9
Scrabble Words With Friends

Quotes with knee-jerk