machicolation

n.

  1. An opening between the corbels which support a projecting parapet, or in the floor of a gallery or the roof of a portal, shooting or dropping missiles upen assailants attacking the base of the walls. Also, the construction of such defenses, in general, when of this character. See Illusts. of Battlement and Castle.
  2. The act of discharging missiles or pouring burning or melted substances upon assailants through such apertures.