Mekong River vs Cathay

Mekong River and Cathay both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mekong River	Yes	No	No	No
Cathay	Yes	No	No	No

Mekong River (noun)	Cathay (noun)
an Asian river; flows through a large delta in southern Vietnam into the South China Sea	a communist nation that covers a vast territory in eastern Asia; the most populous country in the world