A chuck is a special type of "clamp (tool)" vise used to hold an object, usually an object with radial symmetry, especially a cylindrical object. It is most commonly used to hold a rotating tool (such as drill bits on a drill press) or a rotating workpiece (such as the spindle bar of a lathe's fixed headstock). Some chucks can also grip irregularly shaped objects (those lacking radial symmetry). In some applications, the tool or workpiece held by the chuck remains stationary while another tool or workpiece rotates (for example, a drill bit on the tailstock spindle of a lathe, or a circular workpiece being cut by a milling machine).[1]​.

Many chucks have jaws, which are pins that are arranged in a symmetrical radial pattern (like the points of a star) to hold the tool or workpiece. Often the jaws will be tightened or loosened with the help of a chuck wrench, which is a wrench-like tool made for that purpose. However, many clamping chucks are of the keyless variety, and are tightened or loosened by hand force alone. Keyless designs offer the convenience of faster, easier crimping or unclamping at the expense of greater gripping force to hold the tool or workpiece. Collar or collet type chucks, instead of having jaws, have collars, which are flexible sleeves or necks that fit closely around the tool or workpiece and hold it when it is squeezed.