jackknife

1 of 2

noun

jack·knife ˈjak-ˌnīf

Synonyms of jackknife next

: a large strong pocketknife

: a dive executed headfirst in which the diver bends from the waist and touches the ankles while holding the knees unbent and then straightens out

jackknife

2 of 2

verb

jackknifed; jackknifing; jackknifes

intransitive verb

: to double up like a jackknife

jackknifed into a seat beside me, folding up his six feet eight—

Lady Bird Johnson

: to turn and form an angle of 90 degrees or less with each other

—used especially of a tractor-trailer combination

transitive verb

: to cause to double up like a jackknife

: to cut with a jackknife

Examples of jackknife in a Sentence

Verb The truck jackknifed on the icy road.

Recent Examples on the Web

Noun

And the name of the game is squats: Pistol squats, goblet squats with weight, and jackknife crunches are all part of the usual regimen for Naomi. —

Jacqueline Tempera, Women's Health, 28 Apr. 2023 So what’s a jackknife? —

Washington Post, 8 Jan. 2022 Your vehicle could flip on its side or jackknife. —

Wayne K. Roustan, sun-sentinel.com, 26 May 2021 Nissan says the SUVs have jackknife folding keys that may not stay fully open. —

CBS News, 28 Feb. 2023 Some model year 2016 through 2020 Nissan Rogue and 2017 through 2022 Rogue Sports, have jackknife-style keys – the type in which the metal blade of the key flips out from within a plastic key fob. —

Peter Valdes-Dapena, CNN, 28 Feb. 2023 Valdez carved through the Philadelphia Phillies’ lineup with hard sinkers and jackknife curveballs, evening the World Series with a 5-2 victory that was out of his grasp last fall. —

Tyler Kepner, New York Times, 30 Oct. 2022 All told, the Antidote is a one-board jackknife for advanced riders who like to ride fast and take chances. —

Drew Zieff, Outside Online, 18 Oct. 2022

Verb

Two tractor-trailer trucks jackknifed and spilled fuel on Interstate 93 south, tangling traffic on the holiday Tuesday morning, according to state police. —

Sean Cotter, BostonGlobe.com, 4 July 2023 Another truck was jackknifed near I-20 and Bonnie View Road in southeast Oak Cliff. —

Dallas News, 2 Mar. 2023 It’s been a precarious season, with spinouts and jackknifed trailers and frequent whiteout conditions that have forced the closure of the highway. —

St. John Barned-Smith, San Francisco Chronicle, 12 Mar. 2023 The drawings are confusing, but the street view shows a truck jackknifed across a walkway, which is at least a familiar sight. —

William Finnegan, The New Yorker, 6 Mar. 2023 Trying to turn would jackknife the bike, so most riders would brake to a standstill, then try to hop and pivot. —

Peter Rubin, Longreads, 10 Nov. 2022 The driver of the commercial vehicle attempted to take evasive action which caused the truck-tractor and semi-trailer to jackknife across all the westbound lanes of the Interstate. —

Kelli Smith, Dallas News, 16 Apr. 2021 The interesting-looking roofline flows back into a ducktail spoiler with slim taillights that jackknife down the quarter panel. —

Connor Hoffman, Car and Driver, 9 Mar. 2021 The new model meets new, stronger crash-worthiness standards and is designed not to jackknife — guarding against the kind of derailment that killed eight people when Amtrak 188 took a turn too fast near Philadelphia in 2015. —

CBS News, 11 June 2019 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'jackknife.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.