extemporise vs Australian spelling

extemporise is not a noun while Australian spelling is a noun.

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

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

extemporise (verb)	Australian spelling (verb)
perform without preparation