oxbow

Picture a river making a wide U-shaped curve across a flat plain. That curve can be called an oxbow, and if the river later cuts a new, straighter path, the old curve may be left behind as a small curved lake. This is the meaning most people meet in geography. The word can also mean a curved wooden bar that fits around an ox's neck as part of a yoke, which is where the shape-based name comes from.

An oxbow is most often a U-shaped bend in a river or the curved lake that forms when that bend is cut off from the main channel. If you imagine a river slowly winding across the land, you can see how one loop may grow more and more dramatic over time. The water wears away the outer bank, while sand and mud build up on the inner bank, and the narrow strip of land between the two sides of the loop becomes smaller.

Eventually, often during a flood, the river breaks through that narrow strip and takes a shorter path. The old loop is then sealed off by sediment, leaving behind a quiet curved lake. In this sense, the word is common in geography, nature writing, and descriptions of river valleys. People may speak of an oxbow lake, an oxbow pond, or simply an oxbow beside the main river.

The word also has an older farming meaning. An oxbow is the U-shaped wooden piece of a yoke that goes around the neck of an ox and helps hold the yoke in place. That farming sense explains the river sense: people saw the same curved shape in the river bend and used the same name. So depending on the context, oxbow can point either to a curved part of farm equipment or, more commonly today, to a bend or cutoff lake shaped like a horseshoe.