river vs Neosho

river and Neosho both are nouns.

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

river (noun)	Neosho (noun)
a large natural stream of water (larger than a creek)	a river that rises in eastern Kansas and flows eastward into Oklahoma to become a tributary of the Arkansas River