Origin of jackknife

1705–15, Americanism; jack1 (cf. jockteleg) + knife
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for jackknife

plunge, cannonball, gainer

Examples from the Web for jackknife

Historical Examples of jackknife

  • Robert drew a jackknife from his pocket, and did as he was bidden.

    Brave and Bold

    Horatio Alger

  • The black strips at the end of each nail, Martin pared off with his jackknife.


    Mr. and Mrs. Haldeman-Julius

  • He took out his jackknife, and reaching over, severed the traces.

    Cap'n Eri

    Joseph Crosby Lincoln

  • Then he pulled out his jackknife and felt its sharp edge with his thumb.

    The Tale of Timothy Turtle

    Arthur Scott Bailey

  • He carried a whetstone, on which he was sharpening his jackknife.

    Little Prudy

    Sophie May

British Dictionary definitions for jackknife


noun plural -knives

a knife with the blade pivoted to fold into a recess in the handle
a former name for a type of dive in which the diver bends at the waist in midair, with his legs straight and his hands touching his feet, finally straightening out and entering the water headfirst: forward pike dive

verb (intr)

(of an articulated lorry) to go out of control in such a way that the trailer swings round at an angle to the cab
to make a jackknife dive
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012