The Collaborative International Dictionary
Tonneau \Ton`neau"\, n.; pl. Tonneaux. [F.]
In France, a light-wheeled vehicle with square or rounded body and rear entrance.
(Automobiles) Orig., the after part of the body with entrance at the rear (as in vehicle in def. 1); now, one with sides closing in the seat or seats and entered by a door usually at the side, also, the entire body of an automobile having such an after part.
same as Tonne.
n. (plural of tonneau English)