Allure - Wall-walk, passage behind the parapet of a castle wall.

Arrow Loop - A narrow vertical slit cut into a wall through which arrows could be fired.

Bailey - Courtyard.

Ballista - Engine resembling a crossbow, used in hurling missiles or large arrows.

Baluster - A short shaft, such as is used in balustrades, usually thicker in the middle than at the ends.

Barbican - An outwork or forward extension of a castle gateway.

Bastille - Redoubt or outwork.

Bastion - A small tower at the end of a curtain wall or in the middle of the outside wall.

Batter - A sloping part of a curtain wall. The sharp angle at the base of all walls and towers along their exterior surface.

Battlement - Narrow wall built along the outer edge of the wall walk

Bay - A constituent portion or compartment of a building, complete in itself and corresponding to other portions.

Berm - Flat space between the base of the curtain wall and the inner edge of the moat.

Buttery - Room for the service of beverages.

Cat - Assault tower.

Catapult - Stone-throwing engine, usually employing torsion.

Cesspit - The opening in a wall in which the waste from one or more garderobes was collected.

Chamfer - A surface formed by paring off an angle.

Chemise - Inner walled enclosure of a castle.

Corbel - A stone or timber bracket supporting a projection from a wall.

Crenelation - A notched battlement made up of alternate crenels (openings) and merlons (square saw-teeth).

Curtain - Those portions of a fortified wall which connect adjacent flanking-towers.

Daub - A mud of clay mixture applied over wattle to strengthen and seal it.

Dead angle - An angle, the ground contained by which cannot be seen by the defenders, and is therefore indefensible.

Dongjon or keep - The inner stronghold of a castle, usually found in one of the towers.

Drawbridge - A heavy timber platform built to span a moat between a gate house and surrounding land that could be raised when required to block an entrance.

Embrasure - The low segment of the alternating high and low segments of a battlement.

Enceinte - An enclosing wall, usually exterior, of a fortified place.

Escalade - Scaling of a castle wall.

Finial - A slender piece of stone used to decorate the tops of the merlons.

Forebuilding - A projection in front of a keep or donjon, containing the stairs to the main entrance.

Garderobe - Small latrine or toilet, either built into the thickness of the wall or projected out from it.

Gate House - The complex of towers, bridges, and barriers built to protect each entrance through a castle or town wall.

Great Hall - the building in the inner ward that housed the main meeting and dining area for the castle's residents.

Groining - The angular edges formed by the intersection of vaults in a ceiling.

Half-timber - The common form of medieval construction in which walls were made of a wooden frame structure filled with wattle and daub.

Hall - Principal living quarters of a medieval castle or house.

Hall for hynds - Servants' hall.

Herring-bone pattern - The placing of stones aslant in a wall so that each two rows form a succession of angles resembling the backbone of a herring.

Hoarding - A temporary wooden balcony suspended from the tops of walls and towers before a battle, from which missiles and arrows could be dropped or fired accurately toward the base of the wall.

Inner Curtain - The high wall that surrounds the inner ward.

Inner Ward - The open area in the center of a castle.

Keep - See donjon.

Lantern or louvre - A small open turret placed on a roof as an outlet for smoke.

Lights - The spaces between the mullions of a window.

Machicolation - A projection in the battlements of a wall with openings through which missiles can be dropped on besiegers.

Mangonel - A form of catapult.

Merlon - The high part of the square "sawtooth" between crenels in a battlement.

Meurtriere - Arrow loop, slit in battlement or wall to permit firing of arrows, or for observation.

Moat - A deep trench dug around a castle to prevent access from the surrounding land. It could be either left dry or filled with water.

Motte - An earthwork mound on which a castle was built.

Mullions - The vertical divisions of stone or wood between the lights of windows.

Oriel - Projecting room on an upper floor.

Outer Curtain - The wall which enclosed the outer ward.

Outer Ward - The area around the outside of and adjacent to the inner curtain.

Palisade - A sturdy wooden fence usually built to enclose a site until a permanent stone wall could be erected.

Parapet - Protective wall at the top of a fortification, around the outer side of the wall-walk.

Pier - The mass of masonry between arches and other openings.

Pilaster - A square or rectangular pillar, engaged in, and projecting slightly from, a wall.

Portcullis - Vertical sliding wooden grille shod with iron suspended in front of a gateway, let down to protect the gate.

Postern or sally-port - Secondary gate or door.

Putlog Hole - A hole intentionally left in the surface of a wall for insertion of a horizontal pole.

Quoins - Dressed corner-stones.

Ram - Battering-ram.

Rubble - A random mixture of rocks and mortar.

Sapping - Undermining, as of a castle wall.

Scaffolding - The temporary wooden framework built next to a wall to support both workers and materials.

Screens - Wooden partition at the kitchen end of a hall, protecting a passage leading to the buttery, pantry, and kitchen.

Solar - Originally a room above ground level, but commonly applied to the great chamber or a private sitting room off the great hall.

Springald - War engine of the catapult type, employing tension.

Steward - The man responsible for running the day-to-day affairs of the castle in the absence of the lord.

Trebuchet - War engine developed in the Middle Ages employing counterpoise.

Truss - One of the timber frames built to support the roof over the Great Hall.

Turret - A small tower rising above and resting on one of the main towers, usually used as a lookout point.

Ward - Courtyard or bailey.

Wattle - A mat of woven sticks and weeds.