(n.) The act of making into a castle.

abatis advanced work balistraria bank banquette barbed-wire entanglement barbican barricade barrier bartizan bastion breastwork bulwark casemate castellation cheval-de-frise circumvallation contravallation counterscarp crenel curtain demibastion dike drawbridge earthwork embrasure enclosure entanglement escarp escarpment fence fieldwork fortalice fortification glacis loophole lunette machicolation mantelet merlon mound outwork palisade parados parapet portcullis postern gate rampart ravelin redan redoubt sally port scarp sconce stockade tenaille vallation vallum work