Another name for an arquebus. The arquebus, derived from the German Hakenbüchse, was a form of long gun that appeared in Europe during the 15th century. Although the term arquebus was applied to many different forms of firearms from the 15th to 17th centuries, it originally referred to “a hand-gun with a hook-like projection or lug on its under surface, useful for steadying it against battlements or other objects when firing.” These “hook guns” were in their earliest forms defensive weapons mounted on German city walls in the early 1400s, but by the late 1400s had become handheld firearms. A matchlock mechanism was added around 1475 and it became the first firearm with a trigger. The heavy arquebus, known as the musket, was developed to better penetrate plate armor and appeared in Europe around 1521. A standardized arquebus, the caliver, was introduced in the latter half of the 16th century. The name “caliver” is derived from the English corruption of calibre, which is a reference to the gun's standardized bore. The caliver allowed troops to load bullets faster since they fit their guns more easily, whereas before soldiers often had to modify their bullets into suitable fits, or were even forced to make their own prior to battle. The smoothbore matchlock arquebus is considered the forerunner to the rifle and other long gun firearms. Heavy arquebuses mounted on wagons were called arquebus à croc. These carried a ball of about 3.5 ounces (100 g). (source)