What does "mandrel" mean?

Mandrel: (a) A bar of metal inserted in the work to shape it, or to hold it, as in a lathe, during the process of manufacture; an arbor. (b) The live spindle of a turning lathe; the revolving arbor of a circular saw. It is usually driven by a pulley. [Written also manderil.] Mandrel lathe, a lathe with a stout spindle, adapted esp. for chucking, as for forming hollow articles by turning or spinning.