knee jerk

¹ American  

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.

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knee-jerk ² American  

[nee-jurk] / ˈniˌdʒɜrk /

adjective

1. of or relating to a knee-jerk.

2. Informal. reacting according to a certain habitual manner; unthinking.

   a knee-jerk liberal.

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knee jerk British  

noun

1. 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

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1. made or occurring as a predictable and automatic response, without thought

   kneejerk support

Etymology

Origin of knee jerk¹

First recorded in 1875–80

Origin of knee-jerk²

First recorded in 1895–1900

Example Sentences

"Everyone recognizes there is a growing antibiotic resistance crisis, and the knee jerk reaction is to develop new antibiotics," You added.

From Science Daily • Feb. 22, 2024

But a former cabinet minister - strongly opposed to withdrawal - described the idea as "knee jerk nonsense".

From BBC • Aug. 8, 2023

“This is a perfect example of a knee jerk ‘just do something’ mentality,” said Chris McNutt, president of Texas Gun Rights.

From Seattle Times • May 10, 2023

But after the knee jerk reaction, the focus will turn to the ECB and the rate outlook and that will be key driver for European stocks and bonds.”

From Reuters • Apr. 24, 2022

Anxious attention to the knee jerk inhibits it; gritting the teeth or clenching the fist reinforces it.

From Psychology A Study Of Mental Life by Woodworth, Robert S.