cubic millimetre vs British spelling

cubic millimetre and British spelling both are nouns.

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

cubic millimetre (noun)	British spelling (noun)
a metric measure of volume or capacity equal to a cube 1 millimeter on each edge	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')