British spelling vs externalise

British spelling is a noun but externalise is not a noun.

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

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

British spelling (verb)	externalise (verb)
	make external or objective, or give reality to
	regard as objective