an impression of a design, picture, etc. incised or in relief on a surface (as of a gravestone), taken by placing a piece of paper on it and rubbing over the paper with graphite, wax, etc.
See rubbing in American Heritage Dictionary 4
(rŭbˈĭng)
noun
The act of polishing, cleaning, or drying.
A representation of a raised or indented surface made by placing paper over the surface and rubbing the paper gently with a marking agent such as charcoal or chalk.