muffler

noun5

1. •
   Something or someone that muffles.
2. •
   (US) A part of the exhaust pipe of a car that dampens the noise the engine produces.
3. •
   An accessory for a firearm that lessens the noise at the muzzle.
4. •
   A type of scarf.

   • The newcomer took off his cap and his big woollen muffler. His nose was pointed and red. — 1913
5. •
   (slang, rare) A gas mask.