\ ˈnē-ˌjərk How to pronounce knee-jerk (audio) , -ˈjərk \

Definition of knee-jerk

 (Entry 1 of 2)

: readily predictable : automatic knee-jerk reactions also, disapproving : reacting in a readily predictable way The man was such a bleeding-heart knee-jerk liberal that you could predict the rest of the column after reading the first sentence. — Andrew M. Greeley

knee jerk


Definition of knee jerk (Entry 2 of 2)

: an involuntary forward kick produced by a light blow on the tendon below the patella

Synonyms & Antonyms for knee-jerk

Synonyms: Adjective

Antonyms: Adjective

  • nonmechanical
Visit the Thesaurus for More 

Did you know?

Around 1876, the sudden involuntary extension of the leg in response to a light blow just below the knee, which is also known as the patellar reflex, was given the refreshingly simple designation knee jerk. In the 1950s, knee-jerk became an adjective with a figurative sense that doesn't require any actual twitching. "As a salesman, I'm getting a bit weary of the knee-jerk association of a con artist with my professional calling," a correspondent once wrote to The New York Times Magazine. Knee-jerk often has a negative connotation. It usually denotes a too-hasty, impulsive, perhaps even irrational response that is often based on preconceived notions.

Examples of knee-jerk in a Sentence

Recent Examples on the Web: Noun When the term was explained to the uninitiated, the knee jerk response was that paying attention to ESG (or certainly the E and S parts) was a way for companies and investors to lose money. Robert G. Eccles, Forbes, 3 June 2022 Instead of taking the knee jerk reaction of picking up your toys and going home. Laura Johnston, cleveland, 28 Feb. 2022 Despite the substantial losses the crypto market took over the weekend, King said the selloffs were merely a knee jerk reaction that happens from time to time, and not something to worry about in the long term. Fortune, 6 Dec. 2021 This transit can create confusion, and doesn't support knee jerk reactions. Venus Australis,, 19 Oct. 2020 My knee jerk reaction was to call the police and have Elenor call our neighbor friends a couple houses down. Marina Gomberg, The Salt Lake Tribune, 25 Sep. 2020 The Narendra Modi government’s knee jerk decision to curtail ties with China overnight could cost India heavily. Niharika Sharma, Quartz India, 2 July 2020 The knee jerk reaction to provide ventilators for Africa is understandable. Efosa Ojomo, Quartz Africa, 2 May 2020 The knee jerk is, how could a team in UC’s precarious postseason position not try? Paul Daugherty,, 2 Mar. 2020 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'knee-jerk.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of knee-jerk


1958, in the meaning defined above


1849, in the meaning defined above

Learn More About knee-jerk

Time Traveler for knee-jerk

Time Traveler

The first known use of knee-jerk was in 1849

See more words from the same year

Listen to Our Podcast About knee-jerk

Dictionary Entries Near knee-jerk

kneehole desk


knee jerk

See More Nearby Entries 

Statistics for knee-jerk

Cite this Entry

“Knee-jerk.” Dictionary, Merriam-Webster, Accessed 3 Jul. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More Definitions for knee-jerk

knee jerk


Medical Definition of knee jerk

: an involuntary forward jerk or kick produced by a light blow or sudden strain upon the patellar tendon of the knee that causes a reflex contraction of the quadriceps muscle

called also patellar reflex


Test Your Vocabulary

Which Word Does Not Belong?

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
True or False

Test your knowledge - and maybe learn something along the way.

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!