1. (n.) A low wall, especially one serving to protect the edge of a platform, roof, bridge, or the like.

2. (n.) A wall, rampart, or elevation of earth, for covering soldiers from an enemy's fire; a breastwork

abatis advanced work arch dam backstop balistraria bamboo curtain bank banquette bar barbed-wire entanglement barbican barrage barricade barrier bartizan bastion battlement bear-trap dam beaver dam boom breakwater breastwork brick wall buffer bulkhead bulwark casemate cheval-de-frise circumvallation cofferdam contravallation counterscarp curtain dam defense demibastion dike ditch drawbridge earthwork embankment enclosure entanglement escarp escarpment fence fieldwork fortalice fortification gate glacis gravity dam groin hydraulic-fill dam iron curtain jam jetty leaping weir levee logjam loophole lunette machicolation mantelet merlon milldam moat mole mound outwork palisade parados portcullis postern gate rampart ravelin redan redoubt roadblock rock-fill dam sally port scarp sconce seawall shutter dam stockade stone wall tackling tenaille vallation vallum wall weir wicket dam work