Device for igniting gunpowder, invented in the 15th century. The first mechanical ignition system, it represented a major advance in small-arms manufacture. It consisted of an S-shaped arm, called a serpentine, that held a match, and a trigger device that lowered the serpentine so the lighted match would fire the priming powder in the pan at the side of the barrel. The flash in the pan penetrated a small port in the breech and lit the main charge. Though slow and somewhat clumsy, the matchlock was useful because it protected all the working elements inside the lock and freed the user's hand. Early matchlock guns included the musket.