knee jerk

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a reflex extension of the leg resulting from a sharp tap on the patellar tendon
• Syn:
knee-jerk reflex, patellar reflex
• Hypernyms:
reflex, reflex response, reflex action, instinctive reflex, innate reflex,
inborn reflex, unconditioned reflex, physiological reaction