'Silencer' definitions:

Definition of 'silencer'

noun

Short tube attached to the muzzle of a gun that deadens the sound of firing

noun

A tubular acoustic device inserted in the exhaust system that is designed to reduce noise [syn: silencer, muffler]

From: GCIDE

Silencer \Si"lenc*er\, n. One that silences; specif.: (a) The muffler of an internal-combustion engine. (b) Any of various devices to silence the humming noise of telegraph wires. (c) A device for silencing the report of a firearm shooting its projectiles singly, as a tubular attachment for the muzzle having circular plates that permit the passage of the projectile but impart a rotary motion to, and thus retard, the exploding gases. [Webster 1913 Suppl.]

From: GCIDE

Muffler \Muf"fler\, n.
1. Anything used in muffling; esp., a scarf for protecting the head and neck in cold weather; a tippet. [1913 Webster]
Fortune is painted blind, with a muffler above her eyes. --Shak. [1913 Webster]
2. (Mus.) A cushion for terminating or softening a note made by a stringed instrument with a keyboard. [1913 Webster]
3. A kind of mitten or boxing glove, esp. when stuffed. [1913 Webster]
4. One who muffles. [1913 Webster]
5. (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). [Webster 1913 Suppl.]