noun. a large knife with one or more folding blades.
- clasp knife
noun. black-and-white drumfish with an erect elongated dorsal fin.
- genus Equetus
noun. a dive in which the diver bends to touch the ankles before straightening out.
verb. dive into the water bending the body at the waist at a right angle, like a jackknife.
Example sentences of the word jackknife
1. Verb, base form
Avoid exaggerated turns, which can cause your trailer and vehicle to buckle or jackknife, necessitating another attempt.
2. Noun, singular or mass
For a jackknife, hold one knee to the chest and lean backwards for a directed splash.
To tighten your tummy and strengthen your core, Bodybuilding.com recommends butt-ups, crunches, bent-knee hip raises, jackknife sit-ups and the cross-body crunch, which is similar to an air bike.
4. Adjective, comparative
Try incline situps on an incline bench or do jackknife situps from the floor.