ton·neau 
(tə-nō, tŏnō′)
(tə-nō, tŏnō′)n. pl. ton·neaus
1. The rear seating compartment of an early type of automobile.
2. A tight-fitting removable cover, as for the cargo box of a pickup truck, the seating area of a convertible, or the cockpit of a boat.
[French, from Old French tonnel, cask; see TUNNEL.]