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knee-jerk reflex

Cultural  
  1. A sudden involuntary forward movement of the lower leg that can be produced by a firm tap to the tendon located just below the kneecap.


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The term is loosely applied to any response or belief that is automatic rather than thoughtful. In this sense, it is usually a term of reproach: “Smith is a knee-jerk liberal.”

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

My self-deprecating remarks, a knee-jerk reflex with me, didn’t amuse him.

From Los Angeles Times Jan. 12, 2023

“It’s like they go into hibernation from the overwhelming stress. Their brain switches off engagement with their social environment. They don’t respond to pain. Their knee-jerk reflex is absent.”

From Washington Times Sep. 3, 2018

Just as with the knee-jerk reflex, “you have to hit the knee hard enough in the right place, or else nothing happens,” he told me.

From New York Times Apr. 18, 2018

A deep tendon reflex is commonly known as a stretch reflex, and is elicited by a strong tap to a tendon, such as in the knee-jerk reflex.

From Textbooks Jun. 19, 2013

And with a knee-jerk reflex, everybody as usual looks to the young.

From Time Magazine Archive

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