A device attached to the muzzle of a firearm to reduce the sound of its report. The internal design is similar to that of an automobile muffler. Combined with subsonic ammunition, a suppressed firearm can be about as quiet as an air rifle. Sound suppressors are restricted federally, but only illegal in some states.
Also known as a silencer, though the effect is certainly not silence.
Usage note: A sound suppressor may be referred to simply as a “suppressor”. Though that term seems like it could be ambiguous with “flash suppressor“, the word suppressor used alone always refers to a sound suppressor.