The proper term for a silencer, a cylindrical or occasionally rectangular device that attaches to the end of a firearm or is sometimes built into it, to "suppress", or reduce the sound signature of the muzzle blast, thus making the weapon significantly quieter. Requires subsonic ammunition for proper sound reduction. The device itself consists of a tube that attaches to the weapon, usually by threads or a fast-attach device and has any number of designs of baffles, ballistic wipes or mesh to trap and disperse the hot expanding gas, so that it is at a much lower pressure when it leaves the unit, which reduces noise signature and flash. Often, water, lithium grease or coolant are added to "wet" suppressors, to make quieter by further cooling the gases. Revolvers can't be suppressed, but many semi-automatic handguns and most rifles can, with the proper barrels, tuning and ammunition.
Common tool for special operations personnel and assassins for covert elimination of enemies or targets, government agents and SWAT teams for raids, hunters in Europe for noise control and American ranchers and civilian hobbyists who pay a $200 BATFE tax stamp. Popular with more sophisticated criminals as well, who obtain or produce them illegally.
"Okay, with my USP 9mm Compact, custom titanium suppressor and subsonic hollowpoints, the loudest noise these terrorist fucks are gonna hear is a pop, the slide cycling, the round slamming into the hostile's skull and his body hitting the floor. Works for me..." (Jack Bauer kicks the door kicks in, terrorist's head blows out, body hits the ground and craps its pants)
Suppressed .22s, the world's finest pest elimination tool, are so damn quiet that you practically can't hear them, so that nobody around you will know what happened when I shoot you with it and you suddenly fall dead. Food for thought.
Suppressed automatic weapons are some of the most fun that you will ever have with your pants up. Highly recommended, especially for terrified, reality-avoiding liberals who think that everything down to sharp pencils and cocks over 5 inches should be banned. "Oh Jesus, this is so much fun! Quick, somebody call the politicians to pass more laws to save me from myself, before I start thinking for myself again!"
To put silence to and/or bring to an end
Johnny Lovin was suppressed by Jimmy Jerkin's suppressed gun