millimetre vs Australian spelling

millimetre and Australian spelling both are nouns.

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

millimetre (noun)	Australian spelling (noun)
a metric unit of length equal to one thousandth of a meter	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')