American spelling vs diagonalize

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

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

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

American spelling (verb)	diagonalize (verb)
	transform a matrix to a diagonal matrix