in Fortification, a kind of fence made at a passage, retrenchment, &c. to stop up the entry thereof. It is composed of great stakes, about four or five feet high, placed at the distance of eight or ten feet from one another, with tranfums, or overhawt rafter, to stop either horse or foot, that would enter or rush in with violence: in the middle is a moveable bar of wood, that opens or shuts at pleasure. A barrier is commonly set up in a void space, between the citadel and the town, in half moons, &c.