jack-knife

See also: jackknife

English

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jackknife

Wikipedia

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jack-knife (plural jack-knives)

A compact folding knife.
He kept a jack-knife in his pocket for various tasks.
(diving) The front-dive pike, in which the body folds and unfolds.
It took me hundreds of dives to master even the simple jackknife.
(sports) An abdominal exercise where knees and torso are raised from a lying position.
(road transport, colloquial) A semi-trailer truck accident in which the vehicle mimics the closing of a jack-knife.
I have seen several jack-knives along that dangerous stretch of road.
(games) A game of skill played with a pocket knife in which participants try to throw or flip the knife to stick upright in the ground at specified points or areas.
Synonym: mumblety peg
- 1948, Truman Capote, chapter 1, in Other Voices, Other Rooms, Part One:
  Over at the stable, the men joke and drink whiskey, talk crops and play jack-knife […]
(statistics) Alternative spelling of jackknife.

compact folding knife

front-dive pike

abdominal excercise

semi-trailer truck accident

statistics — see jackknife

jack-knife (third-person singular simple present jack-knifes, present participle jack-knifing, simple past and past participle jack-knifed)

To fold in the middle, as a jackknife does.
The cat jackknifed in the air and landed gracefully on its feet.
- 2009, Reif Larsen, The Selected Works of T.S. Spivet, Pinguin Books, page 37:
  There was a world inside that tall grass. You could plop yourself down in the middle of it with the scraggly stems against the back of your neck and the endless grasses rising up and jackknifing against the bigbluesky, and the ranch and all of its players would fade into a distant dream.
- 2026 March 18, Greg Morse, “1996 crash driving freight reforms”, in RAIL, number 1057, page 50:
  Ten of the freight train's wagons had derailed, two of them foul of the Down Fast. At 2308, the TPO struck one of them, causing the locomotive (86239) to jack-knife and turn so that it was almost touching the end wall of a house in The Russetts, a new-build row that sat close to the line.
(colloquial) To cause a semi-trailer truck to fold like a jackknife in a traffic accident.
Before I knew what was happening, I'd jack-knifed the truck.

Before I knew what was happening, I'd jack-knifed.

to fold in the middle

to cause a semi-trailer truck to fold