1. A fine mineral aggregate used as an extender to improve the properties of coating asphalt and plastic asphalt cement.
2. Finely divided inert material (such as pulverized limestone, silica, or colloidal substances) sometimes added to portland cement paint or other materials to reduce shrinkage, improve workability, or act as an extender.
3. A pigmented paste, sometimes colored, rubbed into open-grained wood surfaces to fill the pores prior to finishing.
4. An inert material added to synthetic resin adhesives to improve their properties or reduce cost.
5. A plate which is inserted merely to fill up space; a filler plate.
6. In painting, a composition (often pigmented) used to fill pores or irregularities in a surface in preparation for the application of another coating.