brace. 1. something that holds parts together or in place, as a clasp or clamp. 2. anything that imparts rigidity or steadiness. 3. a device for holding and turning a bit for boring or drilling; bitstock.4. a piece of timber, metal, etc., for supporting or positioning another part of a framework.. (Building) a structural member, such as a beam or prop, used to stiffen a framework. 4. (Instruments) a sliding loop, usually of leather, attached to the cords of a drum: used to change its tension. 5. a pair; two, esp of game birds: a brace of partridges.