jackknife


1jack·knife

noun \ˈjak-ˌnīf\

: a small knife that has a folding blade

: a dive in which you bend from the waist and touch your ankles and then straighten out

Full Definition of JACKKNIFE

1
:  a large strong pocketknife
2
:  a dive executed headfirst in which the diver bends from the waist and touches the ankles while holding the knees unbent and then straightens out

First Known Use of JACKKNIFE

1711

2jackknife

verb

: to bend in the middle like a folding jackknife; especially of a large truck : to have the back part slide out of control toward the front part

Full 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

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