jackknife

• 名词，指一种带有单片或多片刀片的大型折叠刀；也指跳水中的一种姿势，即跳水者在腰部弯曲，用手触碰脚踝，然后伸直身体入水。

A noun referring to a large folding knife with one or more blades, or a type of dive where the diver bends at the waist to touch their ankles before straightening out.

不规则复数

1. Folding knifeB1formal

   A large knife with one or more blades that fold into the handle, typically used for camping or general utility.

   折叠刀

   • He used his jackknife to cut the rope.
   • The scout always carried a jackknife in his pocket.
   • She opened the jackknife to whittle a piece of wood.

   同义词clasp knifepenknifepocketknife

2. Diving positionB2formalsport

   A type of dive in which the diver bends at the waist to touch their ankles before straightening out and entering the water.

   屈体跳水姿势

   • She performed a perfect jackknife off the high board.
   • The coach taught him how to execute a jackknife dive.
   • His jackknife was the highlight of the diving competition.

• 指车辆或物体从中间猛地折弯或折成两段，像折叠刀一样；也指跳水等动作中身体从中间快速弯折。

A verb meaning to bend or fold sharply in the middle, like a jackknife; commonly used for vehicles (e.g., a truck jackknifing) or acrobatic dives.

1. Dive in a jackknife positionB2formalsport

   To dive into the water bending the body at the waist to form a right angle, then straightening before entering the water.

   屈体跳水

   • He jackknifed off the high board into the pool.
   • The diver practiced jackknifing from the three-meter platform.
   • She executed a perfect jackknife dive during the competition.

   同义词pike

2. Fold or buckle suddenlyB2formal

   To bend or collapse in the middle, typically referring to a vehicle such as a truck or trailer folding sharply.

   突然折叠

   • The truck jackknifed on the icy highway, blocking all lanes.
   • An accident occurred when the trailer jackknifed during a sudden stop.
   • The driver lost control and the rig jackknifed across the road.

   同义词bendbucklecollapsedouble overfold

   反义词alignextendstraightenunfold