/ Dictionary / Index K knee jerk: Meaning and Definition of Find definitions for: knee' jerk" Pronunciation: [key] 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. of or pertaining to a knee-jerk. reacting according to a certain habitual manner; unthinking: a knee-jerk liberal. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. kneehole kneel Related Content Daily Word Quiz: pundit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language