A breakwater is a structure built along the coast to protect against strong waves and currents. The term can refer to several different structures, including a GROIN (5 letters), which is a wall built at an angle from the shoreline to reduce erosion; a JETTY (5 letters), which is a wall built out into the water to protect a harbor or river mouth; a GROYNE (6 letters), which is a wall built perpendicular to the shoreline to reduce erosion; a PIER (4 letters), which is a platform built out into the water for docking boats; a MOLE (4 letters), which is a wall built out into the water to protect a harbor or river mouth; a BARRIER (7 letters), which is a wall built along the coast to protect against strong waves and currents; and a seawall (7 letters), which is a wall built along the coast to protect against flooding.