Definitions
1.NounA round object used as an aid for shaping a material, e.g. shaping or enlarging a ring, or bending or enlarging a pipe without creasing or kinking it.
2.NounA tool or component of a tool that guides, grips or clamps something, such as a workpiece to be machined, a machining tool or a part while it is moved.
3.VerbTo shape with a mandrel.