ADJ: Full of rainbows, the epitome of rainbows, of/related to/making one think of rainbows.
(NOTE, this is so totally a word. This is the most real word on the planet. Mister Webster himself used this word.)
Jane: "There is this girl at my school with cool hair. It has many colors - it is so RAINBOWFUL!!"
Dick: "That's cool.. are you a lesbian?"
- - - -
Martha: "Look at that evil little bunny!"
Stewart: "LOOK OUT! It's so rainbowful! I'm blinded!"
Le bunny: * blows Martha and Stewart to pieces *