viverrine vs fossa cat

viverrine and fossa cat both are nouns.

Word	Noun	Adjective	Verb	Adverb
viverrine	Yes	No	No	No
fossa cat	Yes	No	No	No

As nouns, fossa cat is a hyponym of viverrine; that is, fossa cat is a word with a more specific, narrower meaning than viverrine:

viverrine: small cat-like predatory mammals of warmer parts of the Old World
fossa cat: largest carnivore of Madagascar; intermediate in some respects between cats and civets

Other hyponyms of viverrine include civet, civet cat, Cryptoprocta ferox, fossa, genet, Genetta genetta, mongoose, meerkat, mierkat.

viverrine (noun)	fossa cat (noun)
small cat-like predatory mammals of warmer parts of the Old World	largest carnivore of Madagascar; intermediate in some respects between cats and civets