WordNet
locking pliers
n. pliers that can be locked in place
Wikipedia
Locking pliers
Locking pliers, mole grips (mole wrench) or vise-grips are pliers that can be locked into position, using an over-center action. One side of the handle includes a bolt that is used to adjust the spacing of the jaws, the other side of the handle (especially in larger models) often includes a lever to push the two sides of the handles apart to unlock the pliers. "Mole" and "Vise-Grip" are trade names of different brands of locking pliers.
Locking pliers are available in many different configurations, such as needle-nose locking pliers, locking wrenches, locking clamps and various shapes to fix metal parts for welding. They also come in many sizes.