from The American Heritage® Dictionary of the English Language, 4th Edition
- 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.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An underfloor space or flue through which heat from a furnace passes to heat the floor of a room or a bath.
- n. An underfloor heating system, even without such an underfloor space or flue, as adapted to the modern housing, east and west.
from the GNU version of the Collaborative International Dictionary of English
- n. 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.
from The Century Dictionary and Cyclopedia
- n. In architecture, an arched fire-chamber, from which heat is distributed through earthenware pipes to the rooms above it. The term is also sometimes applied to a fireplace, furnace, or oven.
Latin hypocaustum, from Greek hupokauston, from hupokaiein, to light a fire beneath : hupo-, hypo- + kaiein, to burn.(American Heritage® Dictionary of the English Language, Fourth Edition)
Latin hypocaustum, from Ancient Greek ὑπό (hypo, "underneath") + καίειν (kaiein, "to light a fire, burn") (Wiktionary)