sulky, originally a light, open, one-horse, four-wheeled vehicle with its single seat for only one person fixed on its shafts. It is thought to have been invented in the early 19th century by an English physician and was supposedly named for his sulkiness in wishing to sit alone. The sulky was adapted to two wheels and widely used in the United States by doctors and others who had to travel extensively by themselves.
Today the sulky is used primarily in harness racing. Of light metal construction, the racing sulky consists of little more than a U-shaped shaft curving around the narrow seat where the driver perches.