On beaches: a wooden or concrete barrier, usually perpendicular to the shore, intended to prevent the movement of sand along a coast
a construction in or around a harbour designed to break the force of the sea and to provide shelter for vessels lying inside
A breakwater is a wooden or stone wall that extends from the shore into the sea and is built in order to protect a harbour or beach from the force of the waves. a wall built out into the sea to protect the shore from the force of the waves
An offshore structure (such as a wall or jetty) that, by breaking the force of the waves, protects a harbor, anchorage, beach, or shore area (Bates & Jackson 1987)
(1) A structure protecting a HARBOR, anchorage, or BASIN from waves (2) (SMP) Offshore structure aligned parallel to the SHORE, sometimes shore-connected, that provides protection from waves