A crossbow is a type of weapon, based on the bow, consisting of a horizontal bow-like assembly mounted on a stock, that shoots projectiles called bolts or quarrels. The medieval crossbow was called by many names, most of which derived from the word ballista, a torsion siege engine resembling a crossbow. In modern times, although largely supplanted by firearms in most roles, crossbows are still widely used for shooting sports, hunting, and when shooting in relative silence is an important consideration.