A kind of covered shed, formerly used by besiegers in filling up and passing the ditch of a besieged place, sapping and mining the wall, or the like.
Protective movable shed, enabling besiegers to approach close to a castle's walls. (Prestwich, Michael. Armies and Warfare in the Middle Ages: The English Experience, 348) A mobile shelter used in siege warfare, with a strong timber roof and covered in damp hides to make it fireproof. (Seward, Desmond. Henry V: The Scourge of God, 224)