tricolor vs colourful

tricolor is a noun but colourful is not a noun.

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

tricolor (noun)	colourful (noun)
a flag having three colored stripes (especially the French flag)

tricolor (adjective)	colourful (adjective)
having or involving three colors	having much or varied color
	striking in variety and interest
	having color or a certain color; sometimes used in combination