• (n.) The forward extension of the hearth of a blast furnace under the tymp.
(from the article `industrial glass`) From the conditioning chamber, glass is taken in a set of narrow channels, called the forehearth, to the forming machines. The residence time of ...
Fore'hearth` noun (Metal.) The forward extension of the hearth of a blast furnace under the tymp. 
(in a blast furnace or cupola) a reservoir for iron or slag, accessible through a door at hearth level.