Felis onca vs panther

Felis onca and panther both are nouns.

Word	Noun	Adjective	Verb	Adverb
Felis onca	Yes	No	No	No
panther	Yes	No	No	No

As nouns, Felis onca and panther are synonyms defined as:

Felis onca and panther: a large spotted feline of tropical America similar to the leopard; in some classifications considered a member of the genus Felis

Other synonyms of Felis onca include jaguar, Panthera onca.

Felis onca (noun)	panther (noun)
a large spotted feline of tropical America similar to the leopard; in some classifications considered a member of the genus Felis	a leopard in the black color phase
	a large spotted feline of tropical America similar to the leopard; in some classifications considered a member of the genus Felis
	large American feline resembling a lion