gun loop

gun hole, gun loop, gun port, gun slot

A type of embrasure in a structure designed to provide protection in case of enemy attack; the opening enables a defender to fire through a wall, over a wide angle.
References in periodicals archive ?
A hand-carved 15th century window was stolen from a medieval church, on Church Island, Co Leitrim, along with an outer facing stone from a gun loop on the nearby Crane Island.
Also revealed was that during the Second World War a gun loop had been created in an existing wall to form a pill box-type arrangement to defend the High Level Bridge.
Said to have been the hiding place of Oliver Cromwell during the Civil War, the property is built from local stone, the original walls are in excess of one metre thick and three gun loops have also survived.