noun
oxbow lake; crescentic lake; billabong
A crescent-shaped lake formed when a meander of a river is cut off from the main channel. The term 'billabong' is specific to Australian English.
河跡湖は、川の流れが変わった後に残る三日月形の湖です。
An oxbow lake is a crescent-shaped lake left behind after a river changes course.