baneful

from WordNet (r) 3.0 (2006)

baneful
    adj 1: exceedingly harmful [syn: {baneful}, {deadly},
           {pernicious}, {pestilent}]
    2: deadly or sinister; "the Florida eagles have a fierce baleful
       look" [syn: {baleful}, {baneful}]

from The Collaborative International Dictionary of English v.0.48

Baneful \Bane"ful\, a.
   Having poisonous qualities; deadly; destructive; injurious;
   noxious; pernicious. "Baneful hemlock." --Garth. "Baneful
   wrath." --Chapman.
   [1913 Webster] -- {Bane"ful*ly}, adv. --{Bane"ful*ness}, n.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

134 Moby Thesaurus words for "baneful":
      apocalyptic, appalling, atrocious, awful, bad, baleful, beastly,
      black, bodeful, boding, brutal, calamitous, cataclysmal,
      cataclysmic, catastrophic, consuming, consumptive, corroding,
      corrosive, corrupting, corruptive, counterproductive, damaging,
      dark, deadly, death-bringing, deathful, deathly, deleterious,
      demolishing, demolitionary, depredatory, desolating, destroying,
      destructive, detrimental, devastating, dire, direful,
      disadvantageous, disastrous, disserviceable, distressing, doomful,
      dreadful, dreary, evil, evil-starred, fatal, fateful, feral,
      foreboding, fratricidal, gloomy, grim, harmful, hideous,
      horrendous, horrible, horrid, horrific, horrifying, hurtful, ill,
      ill-boding, ill-fated, ill-omened, ill-starred, inauspicious,
      injurious, insalubrious, internecine, killing, lethal, lowering,
      malefic, malevolent, malign, malignant, menacing, mischievous,
      mortal, nihilist, nihilistic, noisome, noxious, of evil portent,
      ominous, pernicious, pestiferous, pestilent, pestilential,
      poisonous, portending, portentous, prejudicial, ravaging, rotten,
      ruining, ruinous, savage, scatheful, self-destructive, shocking,
      sinister, somber, subversionary, subversive, suicidal, terrible,
      threatening, toxic, tragic, unfavorable, unfortunate, unhealthy,
      unlucky, unpromising, unpropitious, unspeakable, untoward,
      unwholesome, vandalic, vandalish, vandalistic, venenate,
      veneniferous, venenous, venomous, vicious, virulent, wasteful,
      wasting, withering