jacknife

Pocket blade tool

A jackknife is a large folding knife with a blade that folds into the handle.

The word extends to anything that bends sharply at a point: a jackknife dive tucks the body at the waist, and when a truck jackknifes, the cab and trailer fold toward each other, usually in a skid.

Also spelled jack-knife or jack knife.

knife

pocketknife

Folding blade with handle

bladeFlat cutting edge
foldingBending something over itself
penknifeSmall folding pocket blade

multitool · whittling · handle · steel · portable · camping · sharp · utility · carving · compact

accident

trailer

Promotional film excerpt

semiLarge freight truck
skidUncontrolled lateral slide
articulatedHaving segments that bend

18-wheeler · rig · overturn · highway · collision · fishtail · braking · tractor-trailer · hinge · swing

dive

pike

Long battlefield spear

tuckFold into concealment
platformRaised flat structure
springboardFlexible platform for jumping

somersault · twisting · inward · reverse · synchronized · diving · competitive · entry · splash · execution

exercise

pike

Long battlefield spear

crunchCrushing, grinding noise
absDistance from zero
coreCentral essential portion

fold · sit-up · bodyweight · mat · plank · obliques · fitness · repetition · stomach · exercise

Opposites

blade mechanism

jacknifefixed blade

Knife without hinge mechanism

sheath knife · hunting knife · dagger · machete · bayonet

diving form

jacknifeswan dive

Arched forward plunge

layout · pencil dive · cannonball · belly flop · back dive

vehicle accident type

jacknifehead-on collision

Direct front-to-front impact

rear-end collision · rollover · sideswipe

Family

jack, knife, jacks, knives, knifed, knifing, jackknife, jackknifed, jackknifing

Familiarity: Top 1,000,000
Profile: Known to kids · Used worldwide · Timeless · Concrete · Everyday, not technical · Rated G