The process used to enhance the condition and thereby the value of a coin by using a brush or a buffing wheel to try to achieve original mint luster or to remove marks and scratches. Not desirable by true coin collectors. The preceding grading descriptions are taken from A Guidebook of United States Coins by R. S. Yeoman.

the process of mechanically moving the surface metal of a coin to simulate luster

Alteration by mechanical polishing to produce a shiny surface