The Collaborative International Dictionary of English v.0.48:

malign \ma*lign"\, a. [L. malignus, for maligenus, i. e., of a
   bad kind or nature; malus bad + the root of genus birth,
   race, kind: cf. F. malin, masc., maligne, fem. See Malice,
   Gender, and cf. Benign, Malignant.]
   1. Having an evil disposition toward others; harboring
      violent enmity; malevolent; malicious; spiteful; --
      opposed to benign.
      [1913 Webster]

            Witchcraft may be by operation of malign spirits.
                                                  --Bacon.
      [1913 Webster]

   2. Unfavorable; unpropitious; pernicious; tending to injure;
      as, a malign aspect of planets.
      [1913 Webster]

   3. Malignant; as, a malign ulcer. [R.] --Bacon.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Malign \Ma*lign"\, v. t. [imp. & p. p. Maligned; p. pr. & vb.
   n. Maligning.] [Cf. L. malignare. See Malign, a.]
   To treat with malice; to show hatred toward; to abuse; to
   wrong; to injure. [Obs.]
   [1913 Webster]

         The people practice what mischiefs and villainies they
         will against private men, whom they malign by stealing
         their goods, or murdering them.          --Spenser.
   [1913 Webster]

   2. To speak great evil of; to traduce; to defame; to slander;
      to vilify; to asperse.
      [1913 Webster]

            To be envied and shot at; to be maligned standing,
            and to be despised falling.           --South.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Malign \Ma*lign"\, v. i.
   To entertain malice. [Obs.]
   [1913 Webster] Malignance

WordNet (r) 3.0 (2006):

malign
    adj 1: evil or harmful in nature or influence; "prompted by
           malign motives"; "believed in witches and malign
           spirits"; "gave him a malign look"; "a malign lesion"
           [ant: benign, benignant]
    2: having or exerting a malignant influence; "malevolent stars";
       "a malefic force" [syn: malefic, malevolent, malign,
       evil]
    v 1: speak unfavorably about; "She badmouths her husband
         everywhere" [syn: badmouth, malign, traduce, drag
         through the mud]

Moby Thesaurus II by Grady Ward, 1.0:

140 Moby Thesaurus words for "malign":
   antagonistic, antipathetic, asperse, atrocious, backbite,
   bad-mouth, baleful, baneful, barbaric, barbarous, befoul, besmirch,
   bespatter, bestial, bitchy, blacken, bloody, blow upon, brutal,
   brutish, calumniate, cast aspersions on, cast reflections on,
   catching, communicable, contagious, corroding, corrosive,
   corrupting, corruptive, counterproductive, cussed, damaging,
   deadly, death-bringing, deathful, deathly, decry, defame, defile,
   deleterious, denigrate, depreciate, derogate, despiteful,
   destructive, detract, detrimental, disadvantageous, disparage,
   disserviceable, distressing, envenomed, evil, fatal, feral, ferine,
   ferocious, fierce, harmful, hateful, hostile, hurtful, infectious,
   infective, inhuman, inimical, iniquitous, injurious, internecine,
   invidious, kill-crazy, killing, lethal, libel, malefic, maleficent,
   malevolent, malicious, malignant, mean, mephitic, merciless,
   miasmal, miasmatic, miasmic, mischievous, mortal, murderous, nasty,
   noisome, noncivilized, noxious, ominous, ornery, pernicious,
   pestiferous, pestilential, pitiless, poisonous, pollute,
   prejudicial, rancorous, revile, ruthless, sanguinary, savage,
   scandal, scandalize, scatheful, slander, slur, smear, smirch, soil,
   spatter, spiteful, stain, sully, taint, tameless, tarnish,
   tear down, toxic, toxicant, toxiferous, traduce, uncivilized,
   ungentle, untamed, venenate, veneniferous, venenous, venomous,
   vicious, vilify, virulent, vituperate, wicked, wild