a firearm that can only be loaded from the muzzle, or the barrel end of the firearm, and uses black powder or black powder substitute
a firearm that is loaded only through the muzzle (the open end of the barrel)
The earliest type of gun, now also popular as modern- made replicas, in which blackpowder and projectile(s) are separately loaded in through the muzzle. The term is often applied to cap-and-ball revolvers where the loading is done not actually through the muzzle but through the open ends of the cylinderþs chambers.
A muzzleloader is any firearm into which the bullet is loaded from the muzzle of the gun (open end of the gun barrel).