in Fortification, a kind of fence erected at a passage, retrenchment, or breach, to stop up the entry there. It is composed of great stakes, about four or five feet in height, placed at the distance of eight or ten feet apart, with transoms or overthwart rafters to stop either horse or foot that would enter or rush in with violence, while in the middle there is a movable bar of wood that opens or shuts at pleasure.