river vs Po

river and Po both are nouns.

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

river (noun)	Po (noun)
a large natural stream of water (larger than a creek)	a European river; flows into the Adriatic Sea
	a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor