Australian spelling vs diphthongise

Australian spelling is a noun but diphthongise is not a noun.

Word	Noun	Adjective	Verb	Adverb
Australian spelling	Yes	No	No	No
diphthongise	No	No	Yes	No

Australian spelling (noun)	diphthongise (noun)
English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')

Australian spelling (verb)	diphthongise (verb)
	change from a simple vowel to a diphthong