n. A structure in which to make and maintain a fire the heat of which is to be used for some mechanical purpose, as the melting of ores or metals, the production of steam as a power, the warming of apartments, the baking of pottery, etc.; specifically, a structure of considerable size built of stone or brick, and usually lined with fire-brick, used for some purpose connected with the operation of smelting metals.n. Figuratively, a place, time, or occasion of severe torture or great trial.To subject to the action of a furnace; figuratively, to heat as if in a furnace.To throw out, as flames or dull reverberations of sound are emitted by a furnace.To issue forth like flames from a furnace.n. A furnace which is continually rotated or revolved to secure thorough mixture or chemical reaction under heat as respects the charge.