Source : Webster's Revised Unabridged Dictionary (1913)

Lesion \Le"sion\ (l[=e]"zh[u^]n), n. [F. l['e]sion, L. laesio,
   fr. laedere, laesum, to hurt, injure.]
   A hurt; an injury. Specifically:
   (a) (Civil Law) Loss sustained from failure to fulfill a
       bargain or contract. --Burrill.
   (b) (Med.) Any morbid change in the exercise of functions or
       the texture of organs. --Dunglison.

Source : WordNet®

lesion
     n 1: any visible abnormal structural change in a bodily part
     2: any break in the skin or an organ caused by violence or
        surgical incision [syn: {wound}]