1. to fold or bend sharply at a joint like a jackknife
2. to form a sharp angle between a truck and its trailer, often causing loss of control
Usage: automotive

Examples

• The gymnast jackknifes her body during the dive.
• He jackknifes forward when he laughs really hard.
• The truck jackknifes on the icy highway.
• The trailer jackknifes behind the cab during the sharp turn.
• She jackknifes her legs up to her chest in the yoga pose.
• The semi jackknifes across both lanes of traffic.