bretesse

from The Century Dictionary.

• noun In medieval fortification: A tower of timber of several stories, crenelated, loopholed, and fitted with other contemporary devices for offense and defense. It differed from the belfry in that it was fixed instead of movable. A construction of timber, of a more or less temporary character, projecting from a wall, etc., especially over a gateway or a passage, which by its aid could be more readily commanded by the garrison through machicolations, etc.