Australian spelling vs off-colour

Australian spelling is a noun but off-colour is not a noun.

Word	Noun	Adjective	Verb	Adverb
Australian spelling	Yes	No	No	No
off-colour	No	Yes	No	No

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

Australian spelling (adjective)	off-colour (adjective)
	in violation of good taste even verging on the indecent