muffler

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

• noun A heavy scarf worn around the neck for warmth.
• noun A device that absorbs noise, especially one used with an internal-combustion engine.

from The Century Dictionary.

• noun A device to deaden or silence the explosive puff of the exhaust of hot gases from an internal-combustion motor such as is used on motor vehicles. The escape of these gases at high temperatures and pressures into the open air is followed by their expansion, with a shock to the displaced air and a noisy report. The muffler compels them to escape slowly and evenly, and by cooling them in the process less change of volume occurs. The simplest type consists of enlargements of the cross-section of the exhaust-pipe, and the discharge through a large number of small orifices. Called silencer in England.

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

• noun Anything used in muffling; esp., a scarf for protecting the head and neck in cold weather; a tippet.
• noun (Mus.) A cushion for terminating or softening a note made by a stringed instrument with a keyboard.
• noun A kind of mitten or boxing glove, esp. when stuffed.
• noun One who muffles.
• noun (Mach.) Any of various devices to deaden the noise of escaping gases or vapors, as a tube filled with obstructions, through which the exhaust gases of an internal-combustion engine, as on an automobile, are passed (called also silencer).

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

• noun US Part of the exhaust pipe of a car that dampens the noise the engine produces.
• noun A type of scarf.

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

• noun a scarf worn around the neck
• noun a device that decreases the amplitude of electronic, mechanical, acoustical, or aerodynamic oscillations
• noun a tubular acoustic device inserted in the exhaust system that is designed to reduce noise