synapsid vs reptile

synapsid and reptile both are nouns.

Word	Noun	Adjective	Verb	Adverb
synapsid	Yes	No	No	No
reptile	Yes	No	No	No

As nouns, reptile is a hypernym of synapsid; that is, reptile is a word with a broader meaning than synapsid:

synapsid: extinct reptile having a single pair of lateral temporal openings in the skull
reptile: any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms

Other hypernyms of synapsid include reptilian.

synapsid (noun)	reptile (noun)
extinct reptile having a single pair of lateral temporal openings in the skull	any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms