Answer: machicolation

AnswerCrossword Clue
machicolationan opening between the corbels which support a projecting parapet, or in the floor of a gallery or the roof of a portal for shooting or dropping missiles upon assailants attacking the base of the walls
machicolation(in medieval fortifications) An opening between the supporting corbels of a projecting parapet or the vault of a gate, through which stones or burning objects could be dropped on attackers
machicolationA projecting structure containing a series of such openings