amortisation vs Australian spelling

amortisation and Australian spelling both are nouns.

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

amortisation (noun)	Australian spelling (noun)
payment of an obligation in a series of installments or transfers	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')
the reduction of the value of an asset by prorating its cost over a period of years