Toxic

toxic
    adj 1: of or relating to or caused by a toxin or poison;
           "suffering from exposure to toxic substances" [ant:
           {atoxic}, {nontoxic}]
    

Toxic \Tox"ic\, Toxical \Tox"ic*al\, a. [L. toxicum poison,
   originally, a poison in which arrows were dipped, Gr.
   toxiko`n (sc. ?) poison for smearing arrows with, fr.
   toxiko`s of or for the bow, from to`xon bow, arrow. Cf.
   {Intoxicate}.]
   Of or pertaining to poison; poisonous; as, toxic medicines.
   [1913 Webster]
    

52 Moby Thesaurus words for "toxic":
      baleful, baneful, catching, communicable, contagious, corroding,
      corrosive, corrupting, corruptive, counterproductive, damaging,
      deadly, deleterious, destructive, detrimental, disadvantageous,
      disserviceable, distressing, envenomed, harmful, hurtful,
      infectious, infective, injurious, lethal, malefic, malevolent,
      malign, malignant, mephitic, miasmal, miasmatic, miasmic,
      mischievous, noisome, noxious, ominous, pernicious, pestiferous,
      pestilential, poison, poisonous, prejudicial, scatheful, toxicant,
      toxiferous, venenate, veneniferous, venenous, venomous, vicious,
      virulent