indigo vs colourful

indigo is a noun but colourful is not a noun.

Word	Noun	Adjective	Verb	Adverb
indigo	Yes	Yes	No	No
colourful	No	Yes	No	No

indigo (noun)	colourful (noun)
a blue-violet color
deciduous subshrub of southeastern Asia having pinnate leaves and clusters of red or purple flowers; a source of indigo dye
a blue dye obtained from plants or made synthetically

indigo (adjective)	colourful (adjective)
having a color between blue and violet	having much or varied color
	striking in variety and interest
	having color or a certain color; sometimes used in combination