- jackknife⇄adj. 1. like a jackknife; turning or rotating like a jackknife.
Ex. a jackknife bridge, a jackknife stage.
2. like that of a jackknife or jackknife dive.
Ex. By a jackknife motion, a skilful athlete can jump over a bar whilst his centr - jackknife⇄jackknife, noun, pl.-knives,verb, -knifed,-knifing,adjective.
- jackknife⇄noun 1. a large, strong pocketknife.
2. a kind of dive in which the diver, keeping his knees straight, touches his feet with his hands in midair and straightens out before entering the water.
3. (Theater.) a rolling platform for changing sc - jackknife⇄v.i. 1. to double up like a jackknife.
2. to dive into the water doubled up like this.
3. to turn at a sharp angle like a jackknife.
Ex. It has been estimated that ... an articulated vehicle jackknifes on average once in every 50,000 - jackknife⇄v.t. 1. to double up like a jackknife.
Ex. Never jackknife an injured person into a car seat.
2. to cut with a jackknife.