WordNet (r) 3.0 (2006):

rule out
    v 1: make impossible, especially beforehand [syn: preclude,
         rule out, close out]
    2: include or exclude by determining judicially or in agreement
       with rules [syn: rule out, rule in]
    3: dismiss from consideration or a contest; "John was ruled out
       as a possible suspect because he had a strong alibi"; "This
       possibility can be eliminated from our consideration" [syn:
       rule out, eliminate, winnow out, reject]

Moby Thesaurus II by Grady Ward, 1.0:

110 Moby Thesaurus words for "rule out":
   abscind, amputate, annihilate, anticipate, avert, ban, bar, bate,
   blot, blot out, bob, cancel, clip, close out, count out, crop,
   cross out, cull, cut, cut away, cut off, cut out, debar, deflect,
   dele, delete, deny, deter, disallow, discourage, disenable,
   dishearten, disqualify, dock, efface, eliminate, embargo, enjoin,
   enucleate, eradicate, erase, estop, except, excise, exclude,
   exclude from, expunge, extinguish, extirpate, fend, fend off,
   forbid, foreclose, forestall, help, inhibit, interdict, isolate,
   keep from, keep off, knock off, lop, make impossible, mutilate,
   nip, obliterate, obviate, outlaw, pare, peel, pick out, preclude,
   prevent, prohibit, proscribe, prune, raze, refuse, reject, repel,
   repress, root out, rub out, save, say no to, scratch, scratch out,
   set apart, set aside, shave, shear, shut out, sponge, sponge out,
   stamp out, stave off, strike off, strike out, strip, strip off,
   suppress, suspend, taboo, take off, take out, truncate, turn aside,
   ward, ward off, wipe out