square centimeter vs American spelling

square centimeter and American spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
square centimeter	Yes	No	No	No
American spelling	Yes	No	No	No

square centimeter (noun)	American spelling (noun)
a unit of area measurement equivalent to 1 centimeter in length multiplied by 1 centimeter in width, where one centimeter equals 0.3937 inch.	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')