jackknife

²jackknife

verb

Definition of JACKKNIFE

transitive verb

1

: to cut with a jackknife

2

: to cause to double up like a jackknife

intransitive verb

1

: to double up like a jackknife <jackknifed into a seat beside me, folding up his six feet eight — Lady Bird Johnson>

2

: to turn and form an angle of 90 degrees or less with each other —used especially of a tractor-trailer combination

Examples of JACKKNIFE

1. The truck jackknifed on the icy road.

First Known Use of JACKKNIFE

1806