American spelling vs diphthongize

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

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

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

American spelling (verb)	diphthongize (verb)
	change from a simple vowel to a diphthong