jack-knife
/ˈdʒæknaɪf; `dʒækˌnaɪf/ n
pl -knives / -naɪvz;-ˌnaɪvz/
1 large pocket-knife with a folding blade （可放衣袋内的）大摺刀.
2 (sport 体) dive in which the body is first bent double and then straightened 屈体跳水. jack-knife v [I]
(esp of an articulated lorry) bend sharply in the middle into a V-shape, usu as the result of an accident （尤指铰接的货车）弯成V字形（通常因交通事故所致）
A heavy lorry has jack-knifed on the motorway, causing long delays. 一辆重型铰接货车在高速公路上撞成V字形, 耽搁了很长时间.