knee jerk

¹

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.

knee-jerk

²

[ nee-jurk ]

adjective

1. of or relating to a knee-jerk.
2. Informal. reacting according to a certain habitual manner; unthinking:

   a knee-jerk liberal.

knee jerk

noun

1. Also calledpatellar reflex physiol an outward reflex kick of the lower leg caused by a sharp tap on the quadriceps tendon just below the patella

adjective

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

   kneejerk support

Word History and Origins

Origin of knee jerk¹

First recorded in 1875–80

Origin of knee jerk²

First recorded in 1895–1900

Example Sentences

Mr Barker denied he made a "knee jerk decision" to leave the Conservatives.

From BBC

The disruption triggered knee jerk reactions from politicians at national and EU level: they committed to rolling back policies, some of them years in the making, on everything from the use of pesticides to limiting the amount of manure that could be spread on fields.

From Seattle Times

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

From Science Daily

Unite's deputy regional secretary, Davy Thompson, said minimum service levels are "the most invidious example of knee jerk legislating this country has seen in a long time".

From BBC

Mr. Berry, a Marine reservist and an attorney, told The Washington Times that the new provision should slow down “knee jerk” reactions from lower-level commanders who receive complaints from “radical activists.”

From Washington Times