'Patellar reflex' definitions:

Definition of 'patellar reflex'

noun

A reflex extension of the leg resulting from a sharp tap on the patellar tendon [syn: knee jerk, knee-jerk reflex, patellar reflex]

From: GCIDE

Reflex \Re"flex\ (r?"fl?ks; formerly r?*fl?ks"), n. [L. reflexus a bending back. See Reflect.]
1. Reflection; the light reflected from an illuminated surface to one in shade. [1913 Webster]
Yon gray is not the morning's eye, 'Tis but the pale reflex of Cynthia's brow. --Shak. [1913 Webster]
On the depths of death there swims The reflex of a human face. --Tennyson. [1913 Webster]
2. (Physiol.) An involuntary movement produced by reflex action. [1913 Webster]
Patellar reflex. See Knee jerk, under Knee. [1913 Webster]