The Collaborative International Dictionary of English v.0.48:

Necrosis \Ne*cro"sis\ (n[-e]*kr[=o]"s[i^]s), n. [NL., fr. Gr.
   ne`krwsis, fr. nekruy^n to make dead, to mortify, nekro`s a
   dead body.]
   1. (Med.) The pathologic death of part of a tissue due to
      irreversible damage. Contrast to necrobiosis, which is a
      normal death of cells in a tissue. Formerly, applied
      primarily to death of bone tissue.
      [1913 Webster +PJC]

   2. (Bot.) A disease of trees, in which the branches gradually
      dry up from the bark to the center.
      [1913 Webster]

WordNet (r) 3.0 (2006):

necrosis
    n 1: the localized death of living cells (as from infection or
         the interruption of blood supply) [syn: necrosis,
         mortification, gangrene, sphacelus]

Moby Thesaurus II by Grady Ward, 1.0:

99 Moby Thesaurus words for "necrosis":
   abscess, ague, anemia, ankylosis, anoxia, apnea, asphyxiation,
   asthma, ataxia, atrophy, backache, bleeding, blennorhea, cachexia,
   cachexy, caries, carrion, chill, chills, colic, constipation,
   convulsion, coughing, cyanosis, decay, decomposition, diarrhea,
   dizziness, dropsy, dry gangrene, dry rot, dysentery, dyspepsia,
   dyspnea, edema, emaciation, fainting, fatigue, fever, fibrillation,
   flux, foulness, gangrene, gas gangrene, growth, hemorrhage,
   high blood pressure, hydrops, hypertension, hypotension, icterus,
   indigestion, inflammation, insomnia, itching, jaundice,
   labored breathing, low blood pressure, lumbago, marasmus,
   moist gangrene, mortification, nasal discharge, nausea,
   necrotic tissue, noma, pain, paralysis, pruritus, putrefaction,
   putrescence, putridity, putridness, rancidity, rancidness,
   rankness, rash, rheum, rot, rottenness, sclerosis, seizure, shock,
   skin eruption, slough, sneezing, sore, spasm, sphacelation,
   sphacelus, spoilage, tabes, tachycardia, tooth decay, tumor,
   upset stomach, vertigo, vomiting, wasting