Overfall is a term that refers to a sudden drop in a natural body of water, such as a river or a waterfall. Some synonyms for overfall include cataract, cascade, waterfall, and torrent. Cataract is a term that refers to a large, steep waterfall, while cascade is a term that refers to a small, gentle waterfall. Waterfall is a more general term that refers to any type of sudden drop in a body of water. Finally, torrent is a term that refers to a rapid or heavy flow of water, often associated with a waterfall or other overfall. Each of these synonyms can be used to describe the sudden movement of water in different ways, depending on the context of the situation.