Triptych - typically an artwork in three panels which are hinged together. I've seen many a triptych as altar pieces in European cathedrals or situated in art galleries. One of my favourites is the one by Hieronymus Bosch, The Garden of Earthly Delights. It's in a gallery in Madrid and I've yet to see it in the flesh (and there's plenty of flesh in it...) but one day I'd like to (use it or lose it, Shaw...) :-)