- a reflex extension of the leg, caused by contraction of the quadriceps, resulting from a sharp tap on the patellar tendon; patellar reflex.
- of or relating to a knee-jerk.
- reacting according to a certain habitual manner; unthinking: a knee-jerk liberal.
- an outward reflex kick of the lower leg caused by a sharp tap on the quadriceps tendon just below the patella
- made or occurring as a predictable and automatic response, without thought
