What is the difference between catchment, drainage basin and watershed

Shed comes to us from three languages. The English shed, noun, is a flat tilted roof. The Old English verb means to remove quickly. The Welsh shed means a place where things have to go one way or another, such as the part in hair or the peak of a roof. The American use of the term has one more meaning. Where the Welsh meaning of watershed would be the ridge line of a mountain, the American term means the catchment basin between two ridgelines. But we still use it in the original meaning when we talk about a "watershed event", also called "fork in the road". (Europeans have no idea what a fork in the road is.) Drainage basin is the same thing from a different viewpoint. Catchment means the area that feeds a river, drainage basin refers to the area drained by the river.