A brig is a type of sailing vessel defined by its rig, which consists of two masts that are both square-rigged. Brigs originated in the second half of the 18th century and were a common type of smaller merchant vessel or warship until the latter part of the 19th century. They were generally larger than schooners and could approach the size of a full-sized, three-masted ship. Brigs varied in length between 75 and 165 ft (23 and 50 m) with tonnages up to 480.
Historically, most brigs were made of wood, although some later brigs were built with hulls and masts of steel or iron. As merchant vessels, brigs mostly plied coastal trading routes, but oceanic voyages were not uncommon, and some were even used for whaling and sealing. Naval brigs carried a battery of 10 to 20 guns on a single deck and served as couriers for battle fleets and training vessels for cadets. In the early U.S. Navy, brigs gained distinction during the War of 1812 in small fleet engagements on the Great Lakes and as merchant raiders in the Atlantic.
In addition to its nautical meaning, a brig can also refer to a prison, especially a naval or military prison. This meaning comes from the fact that two-masted warships known as brigs were historically used as floating prisons.
