The "straight rainbow" is a fairly unusual rank. To have a straight rainbow, you must hold 5 cards that qualify both as either an even or odd straight and as a rainbow. In other words you must hold 5 cards with consecutive even or odd values and each suit is represented at least once. (Please see the sections on "Odd and Even Straights" and "Rainbows" for more precise definitions.) Below is an example of a "Straight Rainbow":
The cards represent each suit at least once and they have consecutive odd values (3, 5, 7, 9, J).