noun
a large, strong, pocketknife
verb
to perform a dive in which the body is bent at the waist and the legs are brought up over the head
-
The diver executed a perfect jackknife off the high diving board.
-
I tried to do a jackknife off the pool edge but ended up belly flopping instead.
-
That guy just did a sick jackknife off the cliff!
-
The company's profits took a jackknife dive after the scandal was exposed.