Source : Webster's Revised Unabridged Dictionary (1913)

Avulsion \A*vul"sion\, n. [L. avulsio.]
   1. A tearing asunder; a forcible separation.

            The avulsion of two polished superficies. --Locke.

   2. A fragment torn off. --J. Barlow.

   3. (Law) The sudden removal of lands or soil from the estate
      of one man to that of another by an inundation or a
      current, or by a sudden change in the course of a river by
      which a part of the estate of one man is cut off and
      joined to the estate of another. The property in the part
      thus separated, or cut off, continues in the original
      owner. --Wharton. Burrill.

Source : WordNet®

avulsion
     n 1: an abrupt change in the course of a stream that forms the
          boundary between two parcels of land resulting in the
          loss of part of the land of one landowner and a
          consequent increase in the land of another
     2: a forcible tearing or surgical separation of one body part
        from another