river vs Merrimack

river and Merrimack both are nouns.

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

river (noun)	Merrimack (noun)
a large natural stream of water (larger than a creek)	a river that rises in south central New Hampshire and flows through Concord and Manchester into Massachusetts and empties into the Atlantic Ocean