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 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.
• 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.

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