American Civil War vs USA

American Civil War and USA both are nouns.

Word	Noun	Adjective	Verb	Adverb
American Civil War	Yes	No	No	No
USA	Yes	No	No	No

American Civil War (noun)	USA (noun)
civil war in the United States between the North and the South; 1861-1865	the army of the United States of America; the agency that organizes and trains soldiers for land warfare
	North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776