definition
strict definition
breakwater
A retaining wall or embankment in a body of water which blocks waves from a sheltered area behind it.
A breakwater is a wall, embankment, or similar structure built in a body of water, usually around the edges of a harbor or recreation area, to block large waves from disturbing the water on its inner side.
The structure interrupts incoming waves so that the water behind it is more sheltered. Harbor protection and recreation areas are common applications.
A wall and an embankment can serve the same wave-blocking purpose. The definition concerns shelter from waves rather than a particular cross-section or construction material.