1) Orthopedic appliances used to support, align, or hold parts of the body in correct position. (Dorland, 28th ed)

2) An appliance that gives support to movable parts (as a joint or a fractured bone), to weak muscles (as in paralysis), or to strained ligaments (as of the lower back).

3) Braces plural: an orthodontic appliance usually of metallic wire that is used especially to exert pressure to straighten misaligned teeth and that is not removable by the patient.