river vs Acheron

river and Acheron both are nouns.

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

river (noun)	Acheron (noun)
a large natural stream of water (larger than a creek)	(Greek mythology) a river in Hades across which the souls of the dead were carried by Charon