fossa vs viverrine

fossa and viverrine both are nouns.

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

As nouns, viverrine is a hypernym of fossa; that is, viverrine is a word with a broader meaning than fossa:

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

Other hypernyms of fossa include viverrine mammal.

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