AISLE: The space between two arcades or between an arcade and an outer wall.
ARCADE: A row of arches supported by columns or piers.
BAILEY: The outer courtyard of a castle; also, the wall surrounding the courtyard
BARBICAN: An outwork from which the gateway or entrance to a castle was defended.
BASTION: A solid masonry projection.
BATTLEMENTS: The notched top of a defensive wall.
CASTELLAN: The officer in charge of a castle.
CURTAIN: The connecting wall joining towers of a castle.
CURTAIN WALL: An exterior wall or a section of that wall between two gates or towers. Some castle had two sets of curtain walls.
DONJON: A great tower in a castle; a keep.
DRAWBRIDGE: A movable bridge. Early drawbridges were removed horizontally like a gangway.
FOSSE: A ditch.
GALLEY: A long passage or room.
HALL: The principal room in the keep, used for receiving guests and for a major entertainments.
KEEP: The strongest tower of a castle. Usually where the lord lived.
LANCET: A tall narrow, pointed window.
LOOP: A narrow opening for the discharge of missiles or arrows
MEURTRIERES: Murder holes, for dropping stones on those below. .
MOAT: A ditch, usually filled with water, surrounding a castle. A common first line of defense.
MOTTE: A high mound of earth on which a lord's residence is placed ussually during the eleventh-and-twelfth-century castles.
MOTTE-AND-BAILEY CASTLE: An early form of castle with a wooden or stone keep.
ORATORY: A small private chapel usually in a house
PALACE: The official residence of a sovereign.
PALISADE: A wooden defensive fence.
PARAPET: A low wall on the outer side of the main wall, protecting the front of the entry walk.
QUADRANGLE: Inner courtyard.
SHELL KEEP: Circular or oval wall surrounding inner portion of castle.
SIEGE: Surrounding and attacking a castle, usually, a prolonged attack.
SLITS: Narrow opening in a wall through which defenders can fire arrows at attackers.
SOLAR: Upper living room of medieval house or cattle, often over the hall.
WALL WALK: A passage along the castle wall.
YETT: Iron gate.