reredos

n. [ From rear + F. dos back, L. dorsum. Cf. Dorsal. ] (Arch.) (a) A screen or partition wall behind an altar. (b) The back of a fireplace. (c) The open hearth, upon which fires were lighted, immediately under the louver, in the center of ancient halls. [ Also spelt reredosse. ] Fairholt. [ 1913 Webster ]