(1):
(n.) To throw out, or exhale, as from a furnace; also, to put into a furnace.
(2):
(n.) A place or time of punishment, affiction, or great trial; severe experience or discipline.
(3):
(n.) An inclosed place in which heat is produced by the combustion of fuel, as for reducing ores or melting metals, for warming a house, for baking pottery, etc.; as, an iron furnace; a hot-air furnace; a glass furnace; a boiler furnace, etc.