achromatic colour vs Australian spelling

achromatic colour and Australian spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
achromatic colour	Yes	No	No	No
Australian spelling	Yes	No	No	No

achromatic colour (noun)	Australian spelling (noun)
a color lacking hue; white or grey or black	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')