A triptych is a series of three separate paintings that together form a story. The word comes from the Greek adjective "triptukhon" (three-fold), from "tri", (three) and "ptysso", (to fold) or "ptyx", (fold) The paintings are usually joined together, with hinges, so that they can be folded shut or displayed open. The middle painting is usually larger, although they can be of equal size.