tonneau UK /təˈnəʊ/US /təˈnoʊ/ noun3 •The rear body or compartment of some types of motor vehicle, especially one containing seats for passengers.From the tonneau of Bentley's car the sheriff and Garland removed the groceries and sick-room supplies, stowing them in the kyacks. — 1920 •Clipping of tonneau cover.Tonneaux were made of the same plasticised canvas material used for soft-tops. — 2003 •An old-style open passenger vehicle with a tonneau (rear compartment with seats).He has spent ten years lovingly restoring a rather luxurious tonneau with teak panelling and leather seats. formstonneaus · tonneaux