1. to fold or bend sharply at a joint like a jackknife
2. of a truck and trailer, to form a sharp angle when the trailer swings around toward the cab
Usage: automotive
3. to dive by bending at the waist and then straightening out
Usage: diving

1. the action of folding or bending sharply

Examples

• The truck was jackknifing on the icy highway.
• She performed a perfect jackknifing dive into the pool.
• The trailer began jackknifing when the driver braked too hard.
• His body was jackknifing forward from the sudden pain.
• The jackknifing of the semi-truck blocked three lanes of traffic.
• The diver’s jackknifing technique impressed the judges.