ˈtänˌō, təˈnō noun
( -s )
Etymology: French, barrel, tun, kind of carriage with rear entrance & seats parallel to the wheels, from Old French tonel, tonnel barrel, tun — more at tunnel
1. : the rear seating compartment of an automobile
tonneau of a limousine
sports car tonneau with removable canvas cover
2. : a shape of watch case or dial resembling a barrel in profile