Arch – A structure that spans a space and supports structure and the weight above it. Usually used to describe a number of features in a castle including windows, doors, blind arches in walls etc. Can be round headed – semi-circular, segmental – partly circular, pointed – arching to a central point. Sometimes with a large keystone.

Arrow Loop – A narrow vertical slit cut into a wall through which lights and air could circulate within the castle. Arrows could be fired from the inside.

Bailey – The ward or courtyard inside the castle walls, includes exercise area, parade ground, emergency corral.

Barbican – The gateway or outworks to a castle.

Barrel vault – Cylindrical roof in the shape of a half barrel.

Batter – An sometimes steeply sloping base of the castle wall or walls associated with the castle.

Battlement – The very top of the castle walls often crowned with raised portions (merlons) between crennellations (the gaps); a narrow wall built along the outer edge of the wall walk for protection against attack.

Biodiversity – the diversity of life, The diversity of all the organisms that occur on Earth. Biodiversity includes the diversity of: Individuals within a species (genetic diversity), species within an ecosystem or habitat (species diversity) and ecosystem or habitats (habitat diversity).

Curtain Wall – A enclosing wall hung surrounding the castle and bailey.

Corbel – A projecting block of stone built into a wall during construction; step-wise construction, as in an arch, roof, etc.

Donjon – A great tower, the residence of the lord.

Drawbridge – A heavy timber platform built to span a moat between a gatehouse and surrounding land or a stone platform and pit that could be raised when required to block an entrance.

Ecology – The branch of Biology that deals with the relations of organisms (living things) to one another and to their physical surroundings.

Ecosystem – A community of organisms all interacting with each other. Complex – it involves all sorts of different species and different groups of species e.g. in a woodland it includes: the birds nesting in the trees; the lichens living on the trees; the tree leaves rotting on the ground and the fungi living on them; the insects living in the trees etc.

Ecosystem Services – All benefits humans receive from ecosystems

Footings – Base of a wall usually used when only the base of the wall remains.

Forebuilding – A smaller building through which the focal building of a site, usually the donjon can be accessed.

Fosse – Ditch.

Garderobe – Technically a dressing room but used to describe a latrine (toilet) either built into the thickness of the wall or projected out from it.

Habitat – The home environment of an organism or a number of organisms. Some species only found in one type of habitat e.g. a whale only found in the sea. Some species are found in a few habitats e.g. some grass species found in both open fields and woodlands.

Jamb – Side posts of arch, door, or window.

Joist – Wall-to-wall timber beams to support floor boards.

Joist-socket – The aperture when the ‘joist’ fitted into the wall, usually square.

Keep – The main tower; now more commonly known as a donjon.

Light – Glazing component part of window, the area which could potentially hold glass.

Lintel – Horizontal stone or beam bridging an opening.

Loop – Narrow, tall opening for light, air or sometimes considered for shooting arrows.

Moat – A deep trench usually filled with water that surrounded a castle.

Mural-stair – Staircase built into the thickness of a wall. Mural meaning ‘of the wall’.

Offset – Ledge marking the narrowing of a wall’s thickness, sometimes used to support a floor.

Oilette – A round opening at the base of a loop.

Parapet – Low wall on outer side of main wall which encloses the wall-walk.

Portcullis – A heavy timber or metal grill at a castle entrance and could be raised or lowered from within the castle. It dropped vertically between grooves to block passages, entrances within the castle or gatehouse.

Rear-arch – Arch on the inner side of a wall or window.

Relieving arch – Arch built in the fabric of a wall for extra support and to relieve pressure.

Voussoir – Wedge-shaped stones in arch.
Wall-plate – Bracket to hold roof –timbers.
Wall-walk – Passage along castle wall; may be roofed, behind the parapet.