Hypocaust \Hyp"o*caust\, n. [L. hypocaustum, Gr. ?; ? under + ? to burn: cf. F. hypocauste.] (Anc. Arch.) A furnace, esp. one connected with a series of small chambers and flues of tiles or other masonry through which the heat of a fire was distributed to rooms above. This contrivance, first used in bath, was afterwards adopted in private houses. [1913 Webster]