knee-jerk

1 of 2

adjective

ˈnē-ˌjərk 

-ˈjərk

: 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

2 of 2

noun

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

Synonyms

Adjective

• automatic
• instinctive
• instinctual
• involuntary
• mechanic
• mechanical
• robotic
• spontaneous

Examples of knee-jerk in a Sentence

Adjective

a colleague known for her knee-jerk rejection of any proposal that she didn't originate

Recent Examples on the Web

Adjective

There was a clear knee-jerk reaction when Lynch won a title the same night of her return, but just 24 hours later, WWE cleared that up with Lynch’s heel turn . —Blake Oestriecher, Forbes.com, 8 June 2025

Guard against knee-jerk reactions, especially concerning money. —Georgia Nicols, Denver Post, 7 June 2025

Noun

Flynn’s suggestion to move the rowdy Southie parade downtown is a knee jerk reaction to appease the upscale yuppie families and other residents who have taken over the traditional working class Irish American neighborhood. —Joe Battenfeld, Boston Herald, 21 Mar. 2024

The thing that keeps you from just acting out on your initial knee jerk reaction and from just acting impulsively. —Alaa Elassar, CNN, 24 July 2023

Word History

First Known Use

Adjective

1958, in the meaning defined above

Noun

1849, in the meaning defined above

Rhymes for knee-jerk

• artwork
• beadwork
• berserk
• breastwork
• brickwork
• brushwork
• casework
• classwork
• clockwork
• coursework
• ductwork
• earthwork

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Kids Definition

knee-jerk

1 of 2 adjective

ˈnē-ˌjərk

: readily predictable : automatic

a knee-jerk reaction to the proposal

knee jerk

2 of 2 noun

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

Medical Definition

knee jerk

noun

: 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