1. a rigid plate, usually of steel in the shape of an arc of a cylinder, coated on the outside of its curved surface with a friction-producing material and tightened against the inside of a brake drum to produce a braking action.
2. (on a bicycle) one of two metal blocks holding rubber pads that, when the hand brake is activated, press against the rotating wheel to produce a braking action. Cf. caliper (def. 6). Also called shoe.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.