The Collaborative International Dictionary of English v.0.48:

Malediction \Mal`e*dic"tion\, n. [L. maledictio: cf. F.
   mal['e]diction. See Maledicent.]
   A proclaiming of evil against some one; a cursing;
   imprecation; a curse or execration; -- opposed to
   benediction.
   [1913 Webster]

         No malediction falls from his tongue.    --Longfellow.
   [1913 Webster]

   Syn: Cursing; curse; execration; imprecation; denunciation;
        anathema.

   Usage: Malediction, Curse, Imprecation, Execration.
          Malediction is the most general term, denoting bitter
          reproach, or wishes and predictions of evil. Curse
          implies the desire or threat of evil, declared upon
          oath or in the most solemn manner. Imprecation is
          literally the praying down of evil upon a person.
          Execration is literally a putting under the ban of
          excommunication, a curse which excludes from the
          kingdom of God. In ordinary usage, the last three
          words describe profane swearing, execration being the
          strongest.
          [1913 Webster]

WordNet (r) 3.0 (2006):

malediction
    n 1: the act of calling down a curse that invokes evil (and
         usually serves as an insult); "he suffered the imprecations
         of the mob" [syn: imprecation, malediction]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "malediction":
   anathema, ban, blasphemy, commination, curse, damnation,
   denunciation, evil eye, excommunication, execration, fulmination,
   hex, imprecation, malison, malocchio, proscription, thundering,
   whammy



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MALEDICTION, Eccl. law. A curse which was anciently annexed to donations
of lands made to churches and religious houses, against those who should
violate their rights.