The term sailboat has a broad meaning generally including yachts, (large sailboats) and smaller vessels of many configurations, Sloop, Cutters, Catboats, Ketch, Yawl, which use wind as the primary means of propulsion. Some of the variations other than size are: hull configuration (monohull, catamaran, trimaran), keel type (full, fin, wing, centerboard etc.), purpose (sport, racing, cruising), number and configuration of masts, and the sail plan. Some of the terms have had various meanings through history, but now have a specific meaning in the parlance of modern yachting. Sailing ships and yachts; each of these terms generally describes a larger vessel than a sailboat; however, the distinctions are blurred and the definitions vary by region and culture. At the smaller end, the distinction among sailboards, windsurfing, and dinghies can be vague.