The word "tonneau" refers to a covering or enclosure typically found on the back of a truck or convertible car, used to protect and cover the cargo area or the backseat when it is not in use.
The Tacoma's list of available options is long, including everything from a tri-fold hard tonneau cover for the bed to leather - trimmed seats to a variety of wheels to blind spot monitors to push - button start. (autoweek.com)
Another first is a tri-fold hard tonneau cover available from the factory. (autofocus.ca)
It's built with a locking tailgate handle and an available hard tri-fold tonneau cover to provide extra security for your cargo. (liptontoyota.com)