River Cocytus vs Greek mythology

River Cocytus and Greek mythology both are nouns.

Word	Noun	Adjective	Verb	Adverb
River Cocytus	Yes	No	No	No
Greek mythology	Yes	No	No	No

River Cocytus (noun)	Greek mythology (noun)
(Greek mythology) a river in Hades that was said to be a tributary of the Acheron	the mythology of the ancient Greeks