Source : Webster's Revised Unabridged Dictionary (1913)

Abrasion \Ab*ra"sion\, n. [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.

Source : WordNet®

abrasion
     n 1: an abraded area where the skin is torn or worn off [syn: {scratch},
           {scrape}, {excoriation}]
     2: erosion by friction [syn: {attrition}, {corrasion}, {detrition}]
     3: the wearing down of rock particles by friction due to water
        or wind or ice [syn: {grinding}, {attrition}, {detrition}]