Breakwater

Noun

 * 1) a construction in or around a harbour designed to break the force of the sea and to provide shelter for vessels lying inside
 * 2)  a low bulkhead across the forecastle deck of a ship which diverts water breaking over the bows into the scuppers
 * 3) On beaches: a wooden or concrete barrier, usually perpendicular to the shore, intended to prevent the movement of sand along a coast.

Thesaurus
abutment, anchorage, anchorage ground, arc-boutant, arch dam, backstop, bamboo curtain, bank, bar, barrage, barrier, basin, beam, bear-trap dam, beaver dam, berth, bill, boom, breastwork, brick wall, buffer, bulkhead, bulwark, buttress, buttress pier, buttressing, cape, chersonese, cofferdam, coral reef, dam, defense, delta, dike, ditch, dock, dockage, dockyard, dry dock, earthwork, embankment, fence, flying buttress, foreland, gate, gravity dam, groin, hanging buttress, harbor, harborage, haven, head, headland, hook, hydraulic-fill dam, iron curtain, jam, jetty, jutty, landing, landing place, landing stage, leaping weir, levee, logjam, marina, milldam, moat, mole, moorings, mound, mull, naze, ness, parapet, peninsula, pier, pier buttress, point, port, portcullis, promontory, protected anchorage, quay, rampart, reef, retaining wall, road, roadblock, roads, roadstead, rock-fill dam, sandspit, seaport, seawall, shipyard, shoulder, shutter dam, slip, spit, spur, stone wall, tongue, wall, weir, wharf, wicket dam, work