In poker, the term rainbow is used in community card games like Hold’em to describe a board that contains all different suits, which means that flushes or flush draws are not possible.
For example, a flop of 2s-4h-Kd would be described as a rainbow flop, as there is only one of each suit, so it’s impossible for any player to have a flush or even a flush draw.
The term rainbow can also be applied to a full runout of five community cards where there may be two cards of the same suit, but since there are no future cards to come, you can’t have a flush in your hand, so for the purposes of the game, this is a rainbow board.
