gill slit vs branchial cleft

gill slit and branchial cleft both are nouns.

Word	Noun	Adjective	Verb	Adverb
gill slit	Yes	No	No	No
branchial cleft	Yes	No	No	No

As nouns, gill slit and branchial cleft are synonyms defined as:

gill slit and branchial cleft: one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes

Other synonyms of gill slit include gill cleft.

gill slit (noun)	branchial cleft (noun)
one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes	one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes