jackknife

/ˈdʒækˌnaɪf/
verb
  1. To fold or bend in the middle, like a jackknife closing.
    • The boat jackknifed as it hit the wave.
    • Be careful not to let the ladder jackknife when you fold it.
    • The trailer jackknifed on the icy road.
  2. To perform a jackknife dive.
    • He practiced jackknifing off the diving board every day.
    • The swimmer jackknifed and then straightened out just before the splash.
    • She jackknifed gracefully into the water.
noun
  1. A large folding knife with a blade that folds into the handle.
    • He pulled out his jackknife to cut the rope.
    • She used a jackknife to sharpen a stick for roasting marshmallows.
    • My grandfather always carried a jackknife in his pocket.
  2. A dive in which the diver bends at the waist, touches the feet, and then straightens out before entering the water.
    • The coach taught the team how to do a jackknife dive.
    • She performed a perfect jackknife off the high board.
    • He won the competition with a clean jackknife into the pool.
  3. A situation in which a truck and its trailer fold together at an angle, like a pocketknife closing.
    • Police closed the road after a jackknife blocked both lanes.
    • Jackknives are a common cause of highway accidents.
    • The truck driver lost control and the rig went into a jackknife.
What does "jackknife" mean? | whatsthatwordmean | whatsthatwordmean