Meaning of knee jerk

knee' jerk"

Pronunciation: [key]
  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

Pronunciation: (nē'jûrk"), [key]
— adj.
  1. of or pertaining to a knee-jerk.
  2. reacting according to a certain habitual manner; unthinking: a knee-jerk liberal.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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