Australian spelling vs amphitheatre

Australian spelling and amphitheatre both are nouns.

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

Australian spelling (noun)	amphitheatre (noun)
English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')	an oval large stadium with tiers of seats; an arena in which contests and spectacles are held
	a sloping gallery with seats for spectators (as in an operating room or theater)