Third-person singular simple present indicative form of jack-knife

a knife intended for survival purposes in a wilderness environment, often in an emergency situation when the user has lost other equipment.

A knife, with a serrated edge, designed to cut bread; sometimes slots into a breadboard.

an enzyme capable of removing specific genes from a sequence of DNA, especially to disable the replication of a virus

A compact folding knife. / The front-dive pike, in which the body folds and unfolds. / (colloquial) A semi-trailer truck accident in which the vehicle mimics the closing of a jack-knife.

To fold in the middle, as a jackknife does. / (colloquial) To cause a semi-trailer truck to fold like a jackknife in a traffic accident.

In painting, a small, edge-less, more or less flexible steel blade used to mix paint on a palette and sometimes to apply paint to a surface.

A knife for cutting and serving fish at table. / A table knife with spatula-shaped blade designed for eating fish.

(medicine) A surgical instrument that uses a high-frequency electric arc to cut through or cut away tissue and at the same time sterilize the edges of the wound and seal cut blood vessels.

(sewing) A type of sharply pressed pleating, especially in a skirt or kilt, in which all of the folds are turned in one direction, with each pleat being three layers of fabric thick.