dive vs jackknife

dive and jackknife both are nouns.

Word	Noun	Adjective	Verb	Adverb
dive	Yes	No	Yes	No
jackknife	Yes	No	Yes	No

As nouns, jackknife is a hyponym of dive; that is, jackknife is a word with a more specific, narrower meaning than dive:

dive: a headlong plunge into water
jackknife: a dive in which the diver bends to touch the ankles before straightening out

As verbs, jackknife is a hyponym of dive; that is, jackknife is a word with a more specific, narrower meaning than dive:

dive: plunge into water
jackknife: dive into the water bending the body at the waist at a right angle, like a jackknife

Other hyponyms of dive include belly-flop.

dive (noun)	jackknife (noun)
a steep nose-down descent by an aircraft	a dive in which the diver bends to touch the ankles before straightening out
a headlong plunge into water	a large knife with one or more folding blades
a cheap disreputable nightclub or dance hall

dive (verb)	jackknife (verb)
drop steeply	dive into the water bending the body at the waist at a right angle, like a jackknife
swim under water
plunge into water