Cocytus vs river

Cocytus and river both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cocytus	Yes	No	No	No
river	Yes	No	No	No

Cocytus (noun)	river (noun)
(Greek mythology) a river in Hades that was said to be a tributary of the Acheron	a large natural stream of water (larger than a creek)