in vs USA

in and USA both are nouns.

Word	Noun	Adjective	Verb	Adverb
in	Yes	Yes	No	Yes
USA	Yes	No	No	No

in (noun)	USA (noun)
a unit of length equal to one twelfth of a foot	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

in (adverb)	USA (adverb)
to or toward the inside of