1. a structure or apparatus in which heat is produced, especially for heating buildings or melting metals
2. a very hot place or situation
Usage: figurative

Examples

• The old furnace in the basement needs to be replaced before winter.
• Steel is melted in a blast furnace at extremely high temperatures.
• We turned up the furnace when the temperature dropped below freezing.
• The factory’s furnace operates at over 2000 degrees Fahrenheit.
• During the heat wave, the city felt like a furnace.
• The blacksmith heated the iron in his furnace until it glowed red.
• Our gas furnace is much more efficient than the old oil burner.