jackknife — ONAD

jackknife /ˈjakˌnīf, ˈdʒækˌnaɪf

▸ noun

(plural jackknives)

1 a knife with a folding blade.

2 a dive in which the body is first bent at the waist and then straightened.

3 Statistics a method of assessing the variability of data by repeating a calculation on the sets of data obtained by removing one value from the complete set.

▸ verb

(jackknifed, jackknifing)

[no object] move one's body into a bent or doubled-up position:

[no object] she jackknifed into a sitting position

the Major jackknifed his thin body at the waist.

▪ [no object] (of an articulated vehicle) bend into a V-shape in an uncontrolled skidding movement.

▪ [no object] (of a diver) perform a jackknife.