1. The separation of electrical charges through surface friction.
2. A process of charge separation that involves the rubbing together of dissimilar material surfaces; such as, blowing dust which may charge fences and other metallic objects to such an extent that slight shocks are felt when touched.

The triboelectric series is a classification scheme for the ordering of the tendency for positive charge acquisition in rubbing. The detailed physical mechanism in triboelectrification is a long unsolved problem.