billionth vs USA

billionth and USA both are nouns.

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

billionth (noun)	USA (noun)
one part in a billion equal parts	the army of the United States of America; the agency that organizes and trains soldiers for land warfare
position 1,000,000,000 in a countable series of things	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

billionth (adjective)	USA (adjective)
the ordinal number of one billion in counting order