rima oris vs oral fissure

rima oris and oral fissure both are nouns.

Word	Noun	Adjective	Verb	Adverb
rima oris	Yes	No	No	No
oral fissure	Yes	No	No	No

As nouns, rima oris and oral fissure are synonyms defined as:

rima oris and oral fissure: the opening through which food is taken in and vocalizations emerge

Other synonyms of rima oris include mouth, oral cavity.

rima oris (noun)	oral fissure (noun)
the opening through which food is taken in and vocalizations emerge	the opening through which food is taken in and vocalizations emerge