full plate armor vs American spelling

full plate armor and American spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
full plate armor	Yes	No	No	No
American spelling	Yes	No	No	No

full plate armor (noun)	American spelling (noun)
a historical type of personal armor made from iron or steel plates entirely encasing the wearer.	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')