Jackknife

Jackknife may refer to:
 * Pocketknife or jackknife, a compact, foldable knife
 * Jackknife Bar, Portland, Oregon, U.S.
 * Jackknifing, a type of crash with articulated vehicle combinations

Film and television

 * Jacknife, a 1989 American film by David Jones
 * "Jack Knife", an episode of NCIS
 * Jackknife, a character on Superjail!

Athletics and sports

 * Jackknife (exercise), an abdominal exercise
 * Jackknife, a kicking move involving 540-degree rotation
 * Jackknife, a type of high dive
 * Jackknife hold, a pinning move in professional wrestling

Other uses

 * Jackknife (statistics), a resampling technique in statistics
 * Jackknife clam, common name for several species of bivalve mollusc