picometer vs American spelling

picometer and American spelling both are nouns.

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

picometer (noun)	American spelling (noun)
a metric unit of length equal to one trillionth of a meter	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')