a knife with the blade pivoted to fold into a recess in the handle
2.
a former name for a type of dive in which the diver bends at the waist in midair, with the legs straight and the hands touching the feet, finally straightening out and entering the water headfirst; forward pike dive
verb(intransitive)
3.
(of an articulated lorry) to go out of control in such a way that the trailer swings round at an angle to the cab