dam, dike, dyke, levee

a barrier constructed to contain the flow of water or to keep out the sea

• Aswan High Dam, Aswan Dam, High Dam — one of the world's largest dams on the Nile River in southern Egypt
• Hoover Dam — a large dam on the Colorado River in Nevada
• milldam — dam to make a millpond to provide power for a water mill
• weir — a low dam built across a stream to raise its level or divert its flow

• barrier — a structure or object that impedes free movement