[hahy-puh-kawst, hip-uh-] 
| a hollow space or system of channels in the floor or walls of some ancient Roman buildings that provided a central heating system by receiving and distributing the heat from a furnace. |
| hy·po·caust (hī'pə-kôst') n. A space under the floor of an ancient Roman building where heat from a furnace was accumulated to heat a room or a bath. [Latin hypocaustum, from Greek hupokauston, from hupokaiein, to light a fire beneath : hupo-, hypo- + kaiein, to burn.] |
hypocaust
in building construction, open space below a floor that is heated by gases from a fire or furnace below and that allows the passage of hot air to heat the room above. This type of heating was developed by the Romans, who used it not only in the warm and hot rooms of the baths but also almost universally in private houses in the northern provinces.
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pəˌkɔst