ul·cer·a·tion /ˌʌlsəˈreʃən/
  潰瘍
  Ul·cer·a·tion n.  Med. The process of forming an ulcer, or of becoming ulcerous; the state of being ulcerated; also, an ulcer.
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  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