From Longman Dictionary of Contemporary Englishjack-knifeˈjack-knife1 noun (plural jack-knives) [countable] 1 Da knife with a blade that folds into its handle2 JUMPa dive in which you bend at the waist when you are in the airjack-knifejack-knife2 verb [intransitive] TTCSLIDEif a large vehicle with two parts jack-knifes, it slides out of control and the back part swings towards the front part The truck skidded on the ice and jack-knifed.→ See Verb table
