theorise vs British spelling

theorise is not a noun while British spelling is a noun.

Word	Noun	Adjective	Verb	Adverb
theorise	No	No	Yes	No
British spelling	Yes	No	No	No

theorise (noun)	British spelling (noun)
	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')

theorise (verb)	British spelling (verb)
to believe especially on uncertain or tentative grounds