opisthodome

n. [ L. opisthodomus, Gr. &unr_;; 'o`pisqen behind + do`mos house: cf. F. opisthodome. ] (Arch.) A back chamber; especially, that part of the naos, or cella, farthest from the main entrance, sometimes having an entrance of its own, and often used as a treasury. [ 1913 Webster ]