An oxbow is a U-shaped wooden or metal frame that fits under and around the neck of an ox or bullock, with its upper ends passing through the bar of the yoke and held in place with a metal key, called a bow pin. The wood most often used is hardwood steamed into shape, like elm or hickory and sometimes willow. A ring is attached by a plate to the centre underside of the yoke, to enable a pair of bullocks to be chained to other pairs in a team and thence hitched to the load.
When rivers meander and are sometimes cut off from their course, they form an oxbow lake which is so named because of the distinctive "U" shape.