British spelling vs decolour

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

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

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

British spelling (verb)	decolour (verb)
	cause to become white or lighter in color