define knee-jerk
Definitions for knee jerk. Here are all the possible meanings and translations of the word knee jerk. Princeton's WordNet(0.00 / 0 votes)Rate this definition: knee jerk, knee-jerk reflex, patellar reflex(noun) a reflex extension of the leg resulting from a sharp tap on the patellar tendon. Knee jerk(n.) emotional and predictable; -- of certain people and their reactions to events. Chaldean Numerology. The numerical value of knee jerk in Chaldean Numerology is: 9.