. (Physiol.) A jerk or forward kick of the lower part of the leg produced by a blow or sudden strain upon the patellar tendon of the knee, which causes a sudden contraction of the quadriceps muscle; the patellar reflex. [ Webster 1913 Suppl. ]
n. emotional and predictable; -- of certain people and their reactions to events. [ PJC ]
. a person of strong liberal convictions who reacts predictably and emotionally to certain events. [ PJC ]
. an immediate unthinking emotional reaction produced by an event or statement to which the reacting person is highly sensitive; -- in persons with strong feelings on a topic, it may be very predictable. [ PJC ]