Definition of jackknife in English:

jackknife

Line breaks: jack|knife
Pronunciation: /ˈdʒaknʌɪf
 
/

noun (plural jackknives)

  • 1A large knife with a folding blade.
    More example sentences
    • Adam had chosen a jackknife rather than a fixed blade.
    • With a jackknife, he whittled a point on a thin green stick pulled from a maple branch.
    • Pen clips, protractors, and jackknives have left hacked shapes to tell people how dull it all was when they sat here.
  • 2A dive in which the body is first bent at the waist and then straightened.
    More example sentences
    • But still, I usually like to lounge about in a chaise lounge or something while everyone else is doing cannonballs and jackknives and freakish flips off the diving board.
    • Though his past leaps of faith have had about as much grace as a jackknife into a leaf-covered pool, bringing Gibbs back has ‘reverse pike triple somersault’ written all over it.
    • With his opponent flat in the center of the ring, Van Dam climbs to the top turnbuckle, springs across the ring crouching and extending his torso like a diver performing a jackknife.
  • 3 Statistics A method of assessing the variability of data by repeating a calculation on the sets of data obtained by removing one value from the complete set.
    More example sentences
    • To evaluate clade support, bootstrap and jackknife analyses were performed in PAUP * using a full heuristic search with 1000 replicates, simple addition sequence, and TBR branch-swapping.
    • Bootstrap and jackknife analyses were performed under the MP criterion, with equal weights for all positions and two random additions of sequences for 200 replicate searches.
    • Higher-order jackknife estimates lead to successively greater reductions in the bias of the estimates of N d, but at the cost of increasing sampling variance.

verb (jackknifes, jackknifing, jackknifed)

[no object] Back to top  
  • 1Move one’s body into a bent or doubled-up position: she jackknifed into a sitting position
    More example sentences
    • With a harsh indrawn breath, I jackknife to a sitting position.
    • Students then jackknife their legs even closer to their bodies to the rhythm of a driving beat.
    • Jimjim's body suddenly jackknifed, wrenching his figure to the side.
  • 1.1(Of an articulated vehicle) bend into a V-shape in an uncontrolled skidding movement: the accident happened when a lorry jackknifed
    More example sentences
    • Mr William tried to slow down by pumping his brakes but the vehicle jackknifed in the road while trying to avoid Mr Utting.
    • The snow came down in handfuls and cars jackknifed to the left and right of us as we drove east on unplowed streets.
    • A double-semi had jackknifed, neatly shutting down four lanes.
  • 1.2(Of a diver) perform a jackknife.

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