Synonyms for Jackknife:

n.

breakdown, bang up, blowout, blindside, broadside, accident, break down, car crash, collision, aquaplane. backstroke, belly flop, bathe, cannonball, the butterfly, breaststroke, crawl, bathing, decompression. flick knife, pocket knife, paper knife, letter opener, palette knife, penknife. jackknife (noun)
clasp knife.
pocket knife (noun)
Barlow knife, case knife.
swan dive (noun)
cannonball.
tool (noun)
calipers, auger, keyhole saw, planer, hacksaw, chain saw, lug wrench, plane, trowel, cold chisel, handsaw, square, wedge, spoke shave, jigsaw, pick, shovel, machete, file, grindstone, tire iron, edger, monkey wrench, shears, spade, Bow-saw, hatchet, saw, vise, axe, grapnel, tool, table saw, scissors, stapler, hedge trimmer, lathe, hammer, hoe, jointer, mallet, posthole auger, level, scroll saw, crowbar, pickax, chisel, spanner, punch, sickle, pipe wrench, sledgehammer, gouge, miter box, ball-peen hammer, band saw, snips, drill, arc welder, circular saw, wrench, buzz saw, screwdriver, Drill press, knife, radial arm saw, scythe, pliers, coping saw, claw hammer, bench drill, ripsaw, crosscut saw, back saw, welder, awl, emery wheel, tin snips, wrecking bar.

Other synonyms:

pocket knife, letter opener, flick knife, paper knife. pocket knife
penknife.
Other relevant words:
bathing, crawl, backstroke, collision, blowout, pocket knife, clasp knife, cannonball, bathe, breakdown, letter opener, paper knife, accident, decompression, blindside, breaststroke, broadside, aquaplane, penknife.

Usage examples for jackknife

  1. He was anxious to give you a kiss; and he's got a lot of pebbles and his favorite jackknife stowed away in a little box, to give you when he sees you! – The Raid From Beausejour; And How The Carter Boys Lifted The Mortgage by Charles G. D. Roberts
  2. He felt in his pocket for his jackknife drew it out and opened it. – Bobby of the Labrador by Dillon Wallace
  3. " That's jus' what I thought," muttered Sube as he practiced " jumping the fence" with his jackknife and at the same time turned an idea over in his mind. – Sube Cane by Edward Bellamy Partridge