Drawbridge(n.) A bridge of which either the whole or a part is made to be raised up, let down, or drawn or turned aside, to admit or hinder communication at pleasure, as before the gate of a town or castle, or over a navigable river or canal.
Thesaurus Entries
Bifrost, abatis, advanced work, balistraria, bank, banquette, barbed-wire entanglement, barbican, barricade, barrier, bartizan, bascule bridge, bastion, bateau bridge, battlement, breastwork, bridge, bulwark, cantilever bridge, casemate, catwalk, cheval-de-frise, circumvallation, contravallation, counterscarp, curtain, demibastion, dike, earthwork, enclosure, entanglement, escarp, escarpment, fence, fieldwork, floating bridge, flyover, footbridge, fortalice, fortification, gangboard, gangplank, gangway, glacis, lift bridge, loophole, lunette, machicolation, mantelet, merlon, mound, outwork, overbridge, overcrossing, overpass, palisade, parados, parapet, pontoon bridge, portcullis, postern gate, rampart, ravelin, redan, redoubt, rope bridge, sally port, scarp, sconce, span, stepping-stone, stepstone, stockade, suspension bridge, swing bridge, tenaille, toll bridge, vallation, vallum, viaduct, work