- A compact folding knife.
- He kept a jack-knife in his pocket for various tasks.
- The front-dive pike, in which the body folds and unfolds.
- It took me hundreds of dives to master even the simple jackknife
- (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.
- (statistics) Alternative spelling of jackknife.
(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.
- (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 like nobody's business.
- Before I knew what was happening, I'd jack-knifed.