a closed vessel or arrangement of vessels and tubes, together with a furnace or other heat source, in which steam or other vapor is generated from water to drive turbines or engines, supply heat, process certain materials, etc. Compare fire-tube boiler, water-tube boiler.
c.1540, from boil (v.). Meaning "vessel for boiling" is from 1725; steam engine sense is from 1757. Boilermaker "shot of whiskey with a glass of beer" is short for boilermaker's delight (1910), strong cheap whiskey, so called in jest from the notion that it would clean the