watercolour vs British spelling

watercolour and British spelling both are nouns.

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

watercolour (noun)	British spelling (noun)
the art or technique of painting with watercolors	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')
a painting produced with watercolors
a water-base paint (with water-soluble pigments); used by artists
water-soluble pigment

watercolour (verb)	British spelling (verb)
paint with watercolors