Hy̆p'o-caust, n.

n. [Gr. ὑπόκαυστον, from ὑποκαίειν, to set on fire from below, from ὑπό, under, and καίειν, to burn; Lat. hypocaustum, Fr. hypocauste.] (Anc. Arch.) A vaulted apartment from which the heat of a fire was distributed to rooms above, by means of earthen tubes. This contrivance, first used in baths, was afterward adopted in private houses.