The term erringer is a genericized misspelling of the last name of Henry Deringer, a famous maker of small pocket pistols in the 1800s. Many copies of the original Philadelphia Deringer pistol were made by other gun makers worldwide, and the name was often misspelled; this misspelling soon became a generic term for any pocket pistol. The original Deringer pistol was a single shot muzzleloading pistol; with the advent of cartridge firearms, pistols began to be produced in the modern form still known as a "derringer".