Silencer
Also: Suppressor · Can
A muzzle device that captures and slows propellant gas, reducing the sound signature of the shot by 25-35 decibels.
“Silencer” is the historical and federal-legal term (NFA Title II). “Suppressor” is what shooters and manufacturers call them today because nothing actually silences a supersonic rifle round. The sonic crack of the bullet is unsuppressable.
A modern rifle suppressor cuts perceived report enough that hearing protection becomes optional in field use (still recommended). It also flattens muzzle rise and reduces concussion to spotters and bystanders, a major quality-of-life upgrade for precision practice.