abrasion

Short definition from Wiktionary

Noun

1. 1
   The act of abrading, wearing, or rubbing off; the wearing away by friction.
2. 2
   The substance thus rubbed off; debris.
3. 3
   The effect of mechanical erosion of rock, especially a river bed, by rock fragments scratching and scraping it.
4. 4
   An abraded, scraped, or worn area.
5. 5
   A superficial wound caused by scraping; an area of skin where the cells on the surface have been scraped or worn away.
6. 6
   The wearing away of the surface of the tooth by chewing.