river vs Monongahela

river and Monongahela both are nouns.

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

river (noun)	Monongahela (noun)
a large natural stream of water (larger than a creek)	a river that rises in northern West Virginia and flows north into Pennsylvania where it joins the Allegheny River at Pittsburgh to form the Ohio River