The Collaborative International Dictionary of English v.0.48:

Gangrene \Gan"grene\, n. [F. gangr[`e]ne, L. gangraena, fr. Gr.
   ?, fr. ? to gnaw, eat; cf. Skr. gras, gar, to devour, and E.
   voracious, also canker, n., in sense 3.] (Med.)
   A term formerly restricted to mortification of the soft
   tissues which has not advanced so far as to produce complete
   loss of vitality; but now applied to mortification of the
   soft parts in any stage.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Gangrene \Gan"grene\, v. t. & i. [imp. & p. p. Gangrened; p.
   pr. & vb. n. Gangrening.] [Cf. F. gangr['e]ner.]
   To produce gangrene in; to be affected with gangrene.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gangrene
    n 1: necrotic tissue; a mortified or gangrenous part or mass
         [syn: gangrene, sphacelus, slough]
    2: the localized death of living cells (as from infection or the
       interruption of blood supply) [syn: necrosis,
       mortification, gangrene, sphacelus]
    v 1: undergo necrosis; "the tissue around the wound necrosed"
         [syn: necrose, gangrene, mortify, sphacelate]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "gangrene":
   break up, canker, caries, carrion, corrupt, corruption, crumble,
   crumble into dust, dandruff, decay, decompose, decomposition,
   disintegrate, dry gangrene, dry rot, excrement, fall into decay,
   fall to pieces, fester, filth, foul matter, foulness, furfur,
   gas gangrene, go bad, go to pieces, mess, mildew, moist gangrene,
   mold, molder, mortification, mortify, muck, mucus, necrose,
   necrosis, necrotic tissue, noma, obscenity, ordure, pus,
   putrefaction, putrefy, putresce, putrescence, putrid matter,
   putridity, putridness, rancidity, rancidness, rankle, rankness,
   rot, rottenness, scurf, scuz, slime, slough, smut, snot, sordes,
   sphacelate, sphacelation, sphacelus, spoil, spoilage, suppurate,
   tooth decay