river vs Lethe

river and Lethe both are nouns.

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

river (noun)	Lethe (noun)
a large natural stream of water (larger than a creek)	(Greek mythology) a river in Hades; the souls of the dead had to drink from it, which made them forget all they had done and suffered when they were alive