knee-jerk reflex(n = noun.act) knee jerk, patellar reflex - a reflex extension of the leg resulting from a sharp tap on the patellar tendon;
is a kind of inborn reflex, innate reflex, instinctive reflex, physiological reaction, reflex, reflex action, reflex response, unconditioned reflex

accommodation reflex, acquired reflex, babinski reflex, conditional reflex, conditioned reflex, defecation reflex, gag reflex, inborn reflex, innate reflex, instinctive reflex, light reflex, micturition reflex, moro reflex, myotactic reflex, patellar reflex, pharyngeal reflex, pilomotor reflex, plantar reflex, pupillary reflex, rectal reflex, reflex, reflex action, reflex angle, reflex arc, reflex camera, reflex epilepsy, rooting reflex, startle reflex, stretch reflex, suckling reflex, unconditioned reflex