The act or process of making a building into a castle.
The addition of battlements to a building, as for example when a feudal manor house needed fortification against border-raider attacks.
Any of a set of slots or grooves in an object, often machined into a metal part, as for example on a castellated nut.
An outwork. A fortification outside a castle used to split an attacking force; composed of two faces, forming a salient angle whose gorge resembles a half-moon