1. a barkentine square-rigged on the mainmast above a gaff mainsail.
2. Also called four-masted brig. a sailing ship having four or more masts, the foremast and mainmast being wholly square-rigged, the others being fore-and-aft-rigged.
3. any sailing ship of three or more masts carrying an otherwise nameless rig.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.