A Glossary of Castle Terminology

Castles

Arbalestina
Cruciform loophole, used by crossbowmen.
Barbican
Advanced fortification work protecting the gateway of a city or castle.
Bartizan

Projecting corner turret

These are particularly notable in the castles of North Wales

Bastion
Fortification work, usually four-sided (tetrahedral) and situated in the corners of a wall, with a sharp point, making possible active defence and flanking fire.
Bastion Tower
Tower projecting from the wall face and functioning as a bastion.
Batter
Outward slope of a revetment.
Battery
Grouping of artillery.
Brattice
Temporary wooden gallery for use in a siege.
Caponnière
Covered passage across a ditch to an outer fortification structure such as a ravelin
Casemate
Covered chamber for musketry or artillery.
Cavalier
Raised structure containing a battery, usually sited above the centre of a bastion. Raising the battery gives a better trajectory.
Citadel
Heavily fortified, independent defensive structure within city walls, dominating an ancient or medieval town; in the bastion system, the strongest part of the fort.
Corbel
Supporting bracket projecting from the face of a wall.
Counterguard
Detached structure protecting a bastion.
Counterscarp
Outer face of a ditch
Couvre Face
Low rampart in the ditch, protecting the face of a ravelin; analogous in function to the counterguard and fausse braye.
Covered Way
Passage along the outer edge of a ditch, protected by a rampart forming the glacis; it is usually some 10 metres wide.
Crownwork
Advanced fortification structure screening the entrance to a bastion fort.
Curtain, Curtain Wall
Stretch of wall betwen two towers.
Donjon
Large main building of a medieval castle. Keep is an alternative name for donjon, particularly widely used down to the 12th century.
Fausse Braye
Low rampart in the ditch, in front of the main fortification.
Glacis
Rampart of the Covered Way, sloping away towards the enemy.

Featured in the song "The British Grenadiers"

Hornwork
'Horned' structure, consisting of two demibastions, one at each end of a curtain.
Keep
See Donjon
Lunette
Triangular (originally crescent-shaped) defensive structure, open at the rear, often flanking a ravelin
Machicolation
Masonry gallery supported by corbels and provided with openings through which missiles could be dropped onto attackers below.
Crenel
The gap in crenellations.

see Merlon

Crenellations

A "toothed" upper edge to a parapet wall.

see Crenel & Merlon

Merlon
The "tooth" in crenellations, alternating with gaps.

see Crenel

Motte
Artificial mound.
Neck Ditch
Ditch cutting across a neck of land, to hinder an enemy's advance.
Bailey
Orillons
Round or squared-off extensions of a bastion's faces, designed to protect its recessed flanks.
Piatta Forma
Fortification structure protecting the curtain between two bastions; it is square or rectangular in plan, or takes the form of a small tetrahedral bastion.
Pilaster
Vertical strip slightly projecting from the wall face.
Place of Arms
Enlarged area in a covered way, where troops could assemble.
Postern
Small gateway in a castle from which the besieged could sally forth.
Ravelin
Fortified structure, more or less triangular in plan, sited in the ditch to defend the curtain.
Redoubt
Detached, independent outwork.
Reduit
Detached, independent outwork.
Retrenchment
Interior defence works, usually consisting of a trench and parapet.
Revetment
Retaining wall; i.e. a wall supporting a bank of earth or mass of water
Roundel
Low, circular, semicircular or U-shaped tower for artillery, projecting from the wall face.
Rustication
Masonry made of rough stone whose outer surface is only roughly dresssed. Also known as en bosse
Scarp
Inner face of a ditch.
Shell Keep
Castle consisting of a high strong ring wall with residential buildings on its inner face.

Examples: Clifford's Tower - York, Arundel Castle

Shield Wall
Exceptionally thick wall, protecting the castle on its most vulnerable side.
Tenaille
Low earth or masonry structure, built in the ditch to protect the curtain.
Trace
Circuit or fortified perimeter, also known as the enceinte.
Traverse
Small bank or wall that cuts across the line of a covered way.

Siege Engines

Catapult
Perrier

A stone throwing engine, powered by teams of soldiers pulling on ropes

Ballista
Trebuchet

A heavy stone throwing engine, powered by a large counterweight

Onager

Roman name for a Mangonel, literally a "wild ass"

Mangonel

A light stone throwing engine, powered by a skein of twisted rope.