Triptych

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)^[1] 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.

A triptych is usually an art work, but the word can be used for anything in three parts which join together to make a single item. ^[2]

1. ↑ "triptych". Online Etymology Dictionary.
2. ↑ "Triptych". Merriam-Webster Dictionary. Retrieved January 28, 2017. Although triptych originally described a specific type of Roman writing tablet that had three hinged sections, it is not surprising that the idea was generalized first to a type of painting, and then to anything composed of three parts.