Source : Webster's Revised Unabridged Dictionary (1913)

Ulceration \Ul`cer*a"tion\, n. [L. ulceratio: cf. F.
   ulc['e]ration.] (Med.)
   The process of forming an ulcer, or of becoming ulcerous; the
   state of being ulcerated; also, an ulcer.

Source : WordNet®

ulceration
     n 1: a circumscribed inflammatory and often suppurating lesion on
          the skin or an internal mucous surface resulting in
          necrosis of tissue [syn: {ulcer}]
     2: the process of ulcer formation; the process of becoming
        ulcerated