A muffler is a device that reduces noise, especially the loud roar coming from a car's engine. Without a muffler, a car would sound like a dozen motorcycles revving at once. The muffler works like a maze inside a metal canister under the car, forcing the hot exhaust gases from the engine to bounce around and lose energy before escaping into the air. This turns a deafening roar into a quieter rumble.

You can usually tell when a car's muffler has a hole in it or has fallen off: the car sounds incredibly loud, almost like it's growling or backfiring. Police officers sometimes pull over drivers with broken mufflers because the noise can disturb entire neighborhoods.

The word can also mean a thick winter scarf wrapped around your neck and lower face to keep warm. Just as a car's muffler quiets engine noise, a winter muffler muffles your voice when you talk through it on a cold morning. Both types of mufflers share the same purpose: dampening or softening something, whether it's sound or cold air.