American spelling vs somber

American spelling is a noun but somber is not a noun.

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

American spelling (noun)	somber (noun)
English orthography used in the United States (characterized by 'analyze', 'center', 'usable')

American spelling (adjective)	somber (adjective)
	lacking brightness or color; dull
	grave or even gloomy in character