HYPOCAUST
Etymology
Noun
hypocaust (plural hypocausts)
An underfloor space or flue through which heat from a furnace passes to heat the floor of a room or a bath.
An underfloor heating system, even without such an underfloor space or flue, as adapted for modern housing.
Synonyms
• (underfloor flue): hippocaust
• (heating system): floor heating, underfloor heating
Source: Wiktionary
Hyp"o*caust, n. Etym: [L. hypocaustum, Gr. hypocauste.] (Anc. Arch.)
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition