lacklustre vs British spelling

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

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

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

lacklustre (adjective)	British spelling (adjective)
lacking luster or shine
lacking brilliance or vitality