clasp knife vs jackknife

clasp knife and jackknife both are nouns.

Word	Noun	Adjective	Verb	Adverb
clasp knife	Yes	No	No	No
jackknife	Yes	No	Yes	No

As nouns, clasp knife and jackknife are synonyms defined as:

clasp knife and jackknife: a large knife with one or more folding blades

clasp knife (noun)	jackknife (noun)
a large knife with one or more folding blades	a dive in which the diver bends to touch the ankles before straightening out
	a large knife with one or more folding blades

clasp knife (verb)	jackknife (verb)
	dive into the water bending the body at the waist at a right angle, like a jackknife