Is a muzzeloader a rifle

It can be either a rifle or a pistol. The Bullet or Ball is loaded through the front of the barrel. These are considered "Black Powder Firearms"

Some muzzleloaders are smooth bores and they can either be shotguns or muskets. In order for a long gun to be a rifle, whether it's a muzzleloader or a modern cartridge gun, is the rifling, or spiral twist in the barrel.