WordNet
pivot joint
n. a freely moving joint in which movement is limited to rotation; "the articulation of the radius and ulna in the arm is a pivot joint" [syn: rotary joint, rotatory joint, articulatio trochoidea]
Wikipedia
Pivot joint
A pivot joint (trochoid joint, rotary joint, lateral ginglymus) is a type of synovial joint. In pivot joints, the axis of a convex articular surface is parallel with the longitudinal axis of the bone.
According to one classification system, a pivot joint like the other synovial joint —the hinge joint has one degree of freedom.
Usage examples of "pivot joint".
So that when the elevator started again, his body swayed easily from the hand that was the pivot joint and up he went.