An arsenal is a comprehensive facility, either privately or publicly owned, where arms and ammunition are manufactured, maintained, repaired, stored, or issued, typically encompassing 100 or more weapons. The term entered English in the 16th century, derived through French and Italian from the Arabic dār aṣ-ṣināʿa, meaning "manufacturing shop."
These crucial installations vary in scale; a first-class arsenal, capable of equipping a large army, includes diverse factories for guns, ammunition, and other materiel, requiring a strategic, secure location and defenses on the scale of a major fortress. In contrast, a second-class arsenal operates with workshops instead of factories. Modern adaptations include "floating armouries" used to store weapons for merchant vessels in international waters. Large arsenals are rigorously subdivided into storekeeping, construction, and administration departments, with historical figures like Frederick Taylor introducing command and control techniques to enhance efficiency at facilities such as the U.S.'s Watertown Arsenal.