tonneau

UK: /ˈtɒnəʊ/ US: (tu nō′)

Inflections of 'tonneau' (n):

tonneaus

npl

tonneaux

npl

WordReference Random House Unabridged Dictionary of American English © 2026

ton•neau  (tu nō′), n., pl. -neaus, -neaux 

(-nōz′). 
1. a rear part or compartment of an automobile body, containing seats for passengers.
2. a complete automobile body having such a rear part.
3. Automotive a waterproof cover, generally of canvas or vinyl, that can be fastened over the cockpit of a roadster or convertible to protect the interior.

• French: literally, cask; Old French tonel. See tunnel
• 1900–05

Collins Concise English Dictionary © HarperCollins Publishers::

tonneau / ˈtɒnəʊ/ noun ( -neaus, -neaux / -nəʊ -nəʊz/)

1. Also called: tonneau cover a detachable cover to protect the rear part of an open car when it is not carrying passengers
2. the part of an open car in which the rear passengers sit

Etymology: 20th Century: from French: special type of vehicle body, from Old French tonnel cask, from tonne tun