tonneau
noun
ton·neau ˈtä-ˌnō 
tə-ˈnō
plural tonneaus
1
a
: a rear seating compartment of an automobile
also : the entire seating compartment
b
: tonneau cover
2
: a shape of watch case or dial resembling a barrel in profile
Example Sentences
Recent Examples on the Web In any event, the indispensable bit is the integrated tonneau. 
Dan Neil, WSJ, 21 Oct. 2021 Each Re-Belle watch is a bold tonneau shaped timepiece that is ergonomically curved for ultimate comfort. Roberta Naas, Forbes, 7 Oct. 2021 Today’s tonneau pickup covers are easier to install, with better access points than ever before. Field & Stream, 19 Mar. 2021 In years past, most tonneau covers were the hatch style, which opened at the tailgate and had hinges just behind the cab. Field & Stream, 19 Mar. 2021 The Boat Tail is a four-seat convertible with an emergency tonneau, just in case the heavens open. Jeremy Taylor, Robb Report, 27 May 2021 Thankfully for pickup owners today, modern tonneau covers used for keeping things dry and safe in the back of your pickup truck are light years ahead of even the models of the not-so-distant past. Field & Stream, 19 Mar. 2021 The best tonneau covers are easy to use, secure your gear, and give you full bed access to your truck. The Editors, Field & Stream, 16 July 2019 The Hummer’s motorized tonneau will offer some security but nothing like its frunk. Roberto Baldwin, Car and Driver, 21 Oct. 2020 See More
Dan Neil, WSJ, 21 Oct. 2021 Each Re-Belle watch is a bold tonneau shaped timepiece that is ergonomically curved for ultimate comfort. Roberta Naas, Forbes, 7 Oct. 2021 Today’s tonneau pickup covers are easier to install, with better access points than ever before. Field & Stream, 19 Mar. 2021 In years past, most tonneau covers were the hatch style, which opened at the tailgate and had hinges just behind the cab. Field & Stream, 19 Mar. 2021 The Boat Tail is a four-seat convertible with an emergency tonneau, just in case the heavens open. Jeremy Taylor, Robb Report, 27 May 2021 Thankfully for pickup owners today, modern tonneau covers used for keeping things dry and safe in the back of your pickup truck are light years ahead of even the models of the not-so-distant past. Field & Stream, 19 Mar. 2021 The best tonneau covers are easy to use, secure your gear, and give you full bed access to your truck. The Editors, Field & Stream, 16 July 2019 The Hummer’s motorized tonneau will offer some security but nothing like its frunk. Roberto Baldwin, Car and Driver, 21 Oct. 2020 See More Word History
Etymology
French, literally, tun, from Old French tonel — more at tunnel entry 1
First Known Use
1901, in the meaning defined at sense 1a