The Collaborative International Dictionary of English v.0.48:

Eradicate \E*rad"i*cate\, v. t. [imp. & p. p. Eradicated; p.
   pr. & vb. n. Eradicating.] [L. eradicatus, p. p. of
   eradicare to eradicate; e out + radix, radicis, root. See
   Radical.]
   1. To pluck up by the roots; to root up; as, an oak tree
      eradicated.
      [1913 Webster]

   2. To root out; to destroy utterly; to extirpate; as, to
      eradicate diseases, or errors.
      [1913 Webster]

            This, although now an old an inveterate evil, might
            be eradicated by vigorous treatment.  --Southey.

   Syn: To extirpate; root out; exterminate; destroy;
        annihilate.
        [1913 Webster]

WordNet (r) 3.0 (2006):

eradicate
    v 1: kill in large numbers; "the plague wiped out an entire
         population" [syn: eliminate, annihilate, extinguish,
         eradicate, wipe out, decimate, carry off]
    2: destroy completely, as if down to the roots; "the vestiges of
       political democracy were soon uprooted" "root out corruption"
       [syn: uproot, eradicate, extirpate, root out,
       exterminate]

Moby Thesaurus II by Grady Ward, 1.0:

109 Moby Thesaurus words for "eradicate":
   abate, abolish, abscind, abstract, amputate, annihilate, avulse,
   ban, bar, blot, bob, cast off, cast out, chuck, clear, clear away,
   clear out, clear the decks, clip, crop, cull, cut, cut away,
   cut off, cut out, deport, deracinate, dig out, dig up, disentangle,
   dispose of, dock, draw, draw out, dredge, dredge up, eject, elide,
   eliminate, enucleate, evolve, evulse, excavate, except, excise,
   exclude, exile, expatriate, expel, exsect, exterminate, extinguish,
   extirpate, extract, extricate, get out, get quit of, get rid of,
   get shut of, gouge out, grub up, isolate, knock off, liquidate,
   lop, mine, mutilate, nip, outlaw, pare, peel, pick out, pluck out,
   pluck up, prune, pull, pull out, pull up, purge, quarry, rake out,
   remove, rip out, root out, root up, rule out, set apart, set aside,
   shave, shear, stamp out, strike off, strike out, strip, strip off,
   sweep away, take off, take out, tear out, throw over,
   throw overboard, truncate, unearth, unravel, uproot, weed out,
   wipe out, withdraw, wrest out