Middle English batelment, from Anglo-French *bataillement, from batailler to fortify with battlements — more at battle
First Known Use: 14th century
Parapet (portion above the roof) of the exterior wall of a fortification, consisting of alternating low portions (crenels) and high portions (merlons). Rooftop defenders would shoot from behind the merlons during times of siege. Medieval battlements were often bracketed out (seecorbel) to form a machicolation (overhang) with holes in its floor through which objects could be dropped on encroachers below.