embrasure

Concise Oxford English Dictionary © 2008 Oxford University Press:
embrasure /ɪmˈbreɪʒə, ɛm-/

▶noun

• 1 an opening in a wall or parapet, used for shooting through.

• 2 an opening or recess around a window or door forming an enlargement of the area from the inside.

– derivatives
embrasured adjective.

– origin C18: from Fr., from obs. embraser ‘widen an opening’, of unknown ultimate origin.