What does abrasion mean?
The definition of abrasion
Ab*ra”sion, n.
Etym: [L. abrasio, fr. abradere. See Abrade.]

1 The act of abrading, wearing, or rubbing off; the wearing away by friction; as, the abrasion of coins.
2 The substance rubbed off. Berkeley.
3 (Med.)
A superficial excoriation, with loss of substance under the form of small shreds. Dunglison.