Meaning of ball bearing

ball' bear'ing

Pronunciation: [key]
— Mach. Mach.
  1. a bearing consisting of a number of hard balls running in grooves in the surfaces of two concentric rings, one of which is mounted on a rotating or oscillating shaft or the like.
  2. any of the balls so used.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.