jackknife
/ˈdʒækˌnaɪf/
NOUN
1. Folding pocketknife
A small knife with a blade that folds into its handle, making it compact and convenient to carry.
1.1. Portable folding knives and cutting tools
Used to describe a compact knife with a hinged blade that folds into its handle when not in use, commonly carried for everyday tasks, camping, or outdoor activities.
Synonyms
- pocketknife
- folding knife
- clasp knife
- penknife
Examples
- He used his jackknife to cut a piece of rope during the camping trip.
- She carried a small jackknife in her backpack for outdoor activities.
- The old jackknife had a wooden handle and a sharp folding blade.
Related Words
NOUN
2. A pike-position diving maneuver
A type of dive in which the diver bends forward at the waist, bringing the legs and upper body together before straightening out for entry into the water.
2.1. Competitive diving and acrobatic movements
Used in swimming and competitive diving to describe a dive performed by folding the body at the hips while keeping the legs relatively straight, then extending the body before entering the water.
Synonyms
- pike dive
- pike
Examples
- The diver performed a perfect jackknife from the high platform.
- She practiced the jackknife repeatedly to improve her diving technique.
- The athlete received high marks for the precision of his jackknife dive.
Related Words
- diving
- front dive
- tuck dive
- somersault
- dive position
- water entry
- diving platform
- springboard
VERB
3. To fold or bend in the middle
To bend or fold sharply at the middle, resembling the closing movement of a folding knife.
3.1. Physical folding and bending
Used to describe a person or object bending sharply at its midpoint, particularly when the upper and lower portions fold toward each other.
Synonyms
- fold
- bend
- double over
- buckle
- collapse
Antonyms
- straighten
- unfold
- extend
- straighten out
Examples
- The gymnast jackknifed her body during the exercise.
- He jackknifed forward to reach the object on the floor.
- The folding mechanism caused the frame to jackknife in the middle.
Related Words
- flexion
- hinge
- curvature
- bending
- folding
- compression
- articulation
3.2. Articulated truck folding in an accident
Used to describe an articulated truck or vehicle combination folding sharply at the joint between the tractor and trailer, usually because of skidding, loss of control, or sudden braking.
Synonyms
- fold
- buckle
- fold up
Examples
- The truck jackknifed on the slippery highway, blocking several lanes.
- The driver lost control and jackknifed the trailer while braking suddenly.
- Heavy rain increased the risk of the vehicle jackknifing on the sharp bend.
Related Words
- semi-trailer
- tractor-trailer
- articulated truck
- skidding
- collision
- trailer
- vehicle accident
- loss of control