1. See siding. 2. A metal coating which is bonded to another metal; see clad alloy. 3. In welding, the deposition of filler metal on a metal surface to obtain desired properties or dimensions; also called surfacing. 4. A nonstructural material (or the surface formed by such a material) used as the exterior covering for the carcass or framework of a building. 5. The surface on which shingles, tiles, or clapboards are fastened. Also see siding and veneer.