diarrhoea vs Australian spelling

diarrhoea and Australian spelling both are nouns.

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

diarrhoea (noun)	Australian spelling (noun)
frequent and watery bowel movements; can be a symptom of infection or food poisoning or colitis or a gastrointestinal tumor	English orthography used in Australia (characterized by 'analyse', 'centre', 'usable')