altar screen

Originally a piece of ornamental precious cloth suspended above the altar at the rear and known as the dossel or dorsal. A permanent or movable structure of metal, stone, or wood was later introduced instead of the cloth; the side facing the church is called the retable; the reverse, the counterretable. When richly ornamented with panels, statues, etc., the structure is called a reredos. Such altar decorations are also known as altar-pieces.