knee-jerk reflex vs patellar reflex

knee-jerk reflex and patellar reflex both are nouns.

Word	Noun	Adjective	Verb	Adverb
knee-jerk reflex	Yes	No	No	No
patellar reflex	Yes	No	No	No

As nouns, knee-jerk reflex and patellar reflex are synonyms defined as:

knee-jerk reflex and patellar reflex: a reflex extension of the leg resulting from a sharp tap on the patellar tendon

Other synonyms of knee-jerk reflex include knee jerk.

knee-jerk reflex (noun)	patellar reflex (noun)
a reflex extension of the leg resulting from a sharp tap on the patellar tendon	a reflex extension of the leg resulting from a sharp tap on the patellar tendon