n. (also Brit. waggon) 1 a four-wheeled vehicle for heavy loads, often with a removable tilt or cover. 2 Brit. a railway vehicle for goods, esp. an open truck. 3 a trolley for conveying tea etc. 4 (in full water-wagon) a vehicle for carrying water. 5 US a light horse-drawn vehicle. 6 colloq. a motor car, esp. an estate car. on the wagon (or water-wagon) sl. teetotal. wagon-roof (or -vault) = barrel vault.
[ earlier wagon, wag(h)en, f. Du. wag(h)en, rel. to OE wgn WAIN ]