Breakwater
a pier, wall, mole, sunken hulk, or anything similar, placed at the entrance of a harbor, at the exposed part of an anchorage, or in any such situation, with the view of deadening the force of the waves which roll in from the ocean. There are several notable breakwaters in this countryone of the longest and most notable being that in Lake Michigan, protecting the harbor of the city of Chicago. The Delaware breakwater in Delaware Bay, is built with sloping sides, being much broader at its base than on top. Other notable breakwaters are those at Cherbourg, France, and Plymouth, England.