saltpeter vs American spelling

saltpeter and American spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
saltpeter	Yes	No	No	No
American spelling	Yes	No	No	No

saltpeter (noun)	American spelling (noun)
(KNO3) used especially as a fertilizer and explosive	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')