jackknifing

Meanings

1. 1verbintransitive

   (of a large truck or its trailer) folding suddenly at a sharp angle while skidding or braking.

   Grammar: No object; the truck or its parts are the subject: The rig jackknifed on the ice.

   Patterns

   • something jackknifes
   • jackknife on something

   The semi truck jackknifed across two lanes of the icy highway.

   Witnesses said the trailer was jackknifing before the driver regained control.

2. 2verbintransitivesport

   (of a person) folding the body sharply at the waist, as in diving or gymnastics.

   Grammar: No object; often used with 'into' for the water or mat: She jackknifed into the pool.

   Patterns

   • jackknife into something
   • jackknife off something

   She jackknifed into the water with hardly a splash.

   The diver was jackknifing off the board when the photo was taken.

3. 3noununcountable

   the act or state of bending sharply in the middle, especially of a truck or train.

   Grammar: Usually uncountable; refers to the event or condition: Jackknifing is common on wet roads.

   Patterns

   • jackknifing of something

   Jackknifing is a serious risk for long trucks on steep, wet hills.

   The accident report blamed jackknifing for the pile-up.

Word forms

Common combinations

jackknife on ice

Big trucks often jackknife on ice when the brakes lock.

jackknife across the road

The bus jackknifed across the road and blocked traffic.

jackknife into the water

He jackknifed into the water from the low board.

a jackknifed truck

A jackknifed truck closed the southbound lanes for hours.

Synonyms and how they differ

fold

Use 'fold' for any bending back on itself; 'jackknife' is specific to vehicles or the body bending sharply at the middle.

skid

'Skid' means sliding sideways without control; a truck can skid without jackknifing, so the words describe different parts of the event.

Word family

jackknife noun

a large folding knife, or the sharp bend itself.

jackknife verb

the base form meaning to bend or fold sharply.

Commonly confused: jackknifing or jackhammer?

Practice

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