barrel roof

基本解釋

A protrusion (56) forming a ridge is disposed on one of the roof of the barrel and the plunger head.
形成脊的突起（56）設在注射筒頂部和柱塞頭中的一個上。
ip.com
A distal end of the barrel defines a roof , and an elongate tip, in fluid communication with the barrel, extends from the roof .
注射筒的遠端限定出頂部和從頂部延伸并與注射筒流體連通的細長尖端。
ip.com
NATO will not attack Syria militarily because Iran and Syria has a Defense Pact. Price of a Barrel of Mideastern Crude will shoot through the roof.
北約不會轟炸敘利亞的，因為敘利亞和伊朗之間有軍事合作協(xié)約，不過此事會造成中東石油的價格漲到屋頂。
blog.sina.com.cn

His new network, RipeTV, offers only short shows packed with cheap thrills--3- to 15-minute snippets of dirt bike racing, lingerie models and guys barrel-rolling off a two-story roof.
FORBES: Attention Deficit Television