heater

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An apparatus that heats or provides heat.
• noun One who heats something or tends a heating apparatus.
• noun Slang A pistol.
• noun Baseball A fastball.

from The Century Dictionary.

• noun One who or that which heats.
• noun Specifically— A furnace, stove, or other device for heating, drying, or warning buildings, rooms, drying-houses, fruit-evaporators, or parts of machines, as the calendering-rolls of a paper-mill.
• noun A small mass of cast-iron designed to be heated and then placed in a hollow fiat-iron or in a coffee-pot, to heat the iron or keep the coffee hot.
• noun In a sugar-making plant, a pan used for the first heating of the cane-juice or syrup; a heating-pan.
• noun In electricity, that part of the Nernst lamp which, in starting, is heated by the electric current and by its heat starts the glower. See Nernst lamp.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who, or that which, heats.
• noun Any contrivance or implement, as a furnace, stove, or other heated body or vessel, etc., used to impart heat to something, or to contain something to be heated.
• noun slang A pistol or other carryable firearm.
• noun See under Feed.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A device that produces and radiates heat, typically to raise the temperature of a room or building.
• noun dated, slang A gun.
• noun baseball (slang) A fastball.
• noun gambling (slang) An extended winning streak.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun device that heats water or supplies warmth to a room
• noun (baseball) a pitch thrown with maximum velocity