[1] : The Collaborative International Dictionary of English v.0.48

annul \annul"\, v. t. imp.  p. p. annulled; p. pr.  vb. n.
   annulling. f. annuler, ll. annullare, annulare, fr. l. ad
   to + nullus none, nullum, neut., nothing. see null, a.
   1. to reduce to nothing; to obliterate.
      1913 webster

            light, the prime work of god, to me's extinct.
            and all her various objects of delight
            annulled.                             --milton.
      1913 webster

   2. to make void or of no effect; to nullify; to abolish; to
      do away with; -- used appropriately of laws, decrees,
      edicts, decisions of courts, or other established rules,
      permanent usages, and the like, which are made void by
      component authority.
      1913 webster

            do they mean to annul laws of inestimable value to
            our liberties?                        --burke.
      1913 webster

   syn: to abolish; abrogate; repeal; cancel; reverse; rescind;
        revoke; nullify; destroy. see abolish.
        1913 webster
see also:
annulled annulling null abolish 

[2] : WordNet (r) 2.0

annul
     v 1: declare invalid; "the contract was annulled"; "void a plea"
          syn: invalidate, quash, void, avoid, nullify
          ant: validate
     2: annul by recalling or rescinding; "he revoked the ban on
        smoking"; "lift an embargo"; "vacate a death sentence"
        syn: revoke, lift, countermand, reverse, repeal,
         overturn, rescind, vacate
     also: annulling, annulled
see also:
invalidate quash void avoid nullify validate 
revoke lift countermand reverse repeal 
overturn rescind vacate annulling annulled 

[3] : Moby Thesaurus II by Grady Ward, 1.0

77 moby thesaurus words for "annul":
   abate, abolish, abrogate, abstract, annihilate, black out,
   blot out, bring to naught, bring to nothing, buffer, cancel,
   cancel out, come to nothing, counteract, counterbalance,
   countercheck, countermand, counterorder, delete, disannul,
   discharge, dispose of, dissolve, divorce, do away with, efface,
   eliminate, expunge, extinguish, frustrate, grant a divorce,
   grant an annulment, invalidate, make void, negate, negativate,
   negative, neutralize, nullify, obliterate, obtain a divorce,
   offset, outweigh, overbalance, override, overrule, part,
   put asunder, put away, quash, recall, recant, redress, remove,
   renege, repeal, rescind, retract, reverse, revoke, separate,
   set aside, split up, stultify, sue for divorce, suspend, thwart,
   undo, unmarry, untie the knot, vacate, vitiate, void, waive,
   wipe out, withdraw, write off

Annul >> A Words
Annul, definition of term: Annul
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