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.