Jack-knife
noun, verb, slang ·Moderate ·College level
Definitions
- 1 A compact folding knife.
"He kept a jack-knife in his pocket for various tasks."
- 2 The front-dive pike, in which the body folds and unfolds.
"It took me hundreds of dives to master even the simple jackknife."
- 3 A semi-trailer truck accident in which the vehicle mimics the closing of a jack-knife. colloquial
"I have seen several jack-knives along that dangerous stretch of road."
- 4 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; mumblety-peg.
"Over at the stable, the men joke and drink whiskey, talk crops and play jack-knife ..."
- 5 Alternative spelling of jackknife. alt-of, alternative
- 1 To fold in the middle, as a jackknife does.
"The cat jackknifed in the air and landed gracefully on its feet."
- 2 To cause a semi-trailer truck to fold like a jackknife in a traffic accident. colloquial
"Before I knew what was happening, I'd jack-knifed the truck."
Synonyms
All synonymsExample
More examples"But with me there is a limit, and when I find a man who keeps his cigars in the coal-scuttle, his tobacco in the toe end of a Persian slipper, and his unanswered correspondence transfixed by a jack-knife into the very centre of his wooden mantelpiece, then I begin to give myself virtuous airs."
Related phrases
More for "jack-knife"
Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.