A jackknife is a large, sturdy pocketknife with one or more folding blades that pivot into the handle, often featuring a main clip point blade and a smaller secondary blade. It is also used to describe a "pike" dive, a surgical position, or a vehicle trailer accident
Knife: Traditionally a folding pocket knife with a bolster at one end, designed for versatile, daily tasks.Dive: A maneuver in which a diver bends at the waist to touch their ankles in midair, then straightens out before entering the water.Vehicle Accident: When a towing vehicle and its trailer skid, causing the trailer to swing around and face backward, folding at an acute angle.Medical Term: The jackknife position is a surgical, prone position with hips flexed 90 degrees.Statistic Method: A data resampling technique used for estimation