cubic kilometre vs British spelling

cubic kilometre and British spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
cubic kilometre	Yes	No	No	No
British spelling	Yes	No	No	No

cubic kilometre (noun)	British spelling (noun)
a unit of capacity equal to the volume of a cube one kilometer on each edge	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')