virulent

virulent
    adj 1: extremely poisonous or injurious; producing venom;
           "venomous snakes"; "a virulent insect bite" [syn:
           {deadly}, {venomous}, {virulent}]
    2: infectious; having the ability to cause disease [ant:
       {avirulent}]
    3: harsh or corrosive in tone; "an acerbic tone piercing
       otherwise flowery prose"; "a barrage of acid comments"; "her
       acrid remarks make her many enemies"; "bitter words";
       "blistering criticism"; "caustic jokes about political
       assassination, talk-show hosts and medical ethics"; "a
       sulfurous denunciation"; "a vitriolic critique" [syn:
       {acerb}, {acerbic}, {acid}, {acrid}, {bitter}, {blistering},
       {caustic}, {sulfurous}, {sulphurous}, {virulent},
       {vitriolic}]
    

Virulent \Vir"u*lent\, a. [L. virulentus, fr. virus poison: cf.
   F. virulent. See {Virus}.]
   1. Extremely poisonous or venomous; very active in doing
      injury.
      [1913 Webster]

            A contagious disorder rendered more virulent by
            uncleanness.                          --Sir W.
                                                  Scott.
      [1913 Webster]

   2. Very bitter in enmity; actuated by a desire to injure;
      malignant; as, a virulent invective.
      [1913 Webster]
    

149 Moby Thesaurus words for "virulent":
      acerb, acerbate, acerbic, acid, acidic, acidulent, acidulous,
      acrid, acrimonious, acute, antagonistic, antipathetic, astringent,
      baleful, baneful, belligerent, biting, bitter, brutal, burning,
      catching, caustic, choleric, clashing, colliding, communicable,
      conflicting, contagious, corroding, corrosive, corrupting,
      corruptive, counterproductive, cutting, damaging, dangerous,
      deadly, death-bringing, deathful, deathly, deleterious, despiteful,
      destructive, detrimental, disadvantageous, disserviceable,
      distressing, double-edged, drastic, edged, embittered, envenomed,
      escharotic, excessive, exorbitant, extravagant, extreme, fatal,
      feral, fierce, full of hate, furious, great, harmful, harsh,
      hateful, hostile, hurtful, immoderate, incisive, infectious,
      infective, injurious, intemperate, intense, internecine, keen,
      killing, lethal, malefic, malevolent, malicious, malign, malignant,
      mephitic, miasmal, miasmatic, miasmic, mischievous, mordacious,
      mordant, mortal, nasty, noisome, noxious, ominous, outrageous,
      penetrating, pernicious, pestiferous, pestilential, piercing,
      poignant, poison, poisonous, prejudicial, quarrelsome, rancorous,
      rankled, repugnant, resentful, resenting, rigorous, rough,
      sarcastic, savage, scatheful, scathing, septic, set against,
      severe, sharp, sore, spiteful, splenetic, splitting, stabbing,
      stewing, stinging, strident, stringent, tart, tough, toxic,
      toxicant, toxiferous, trenchant, unconscionable, unfriendly,
      unhealthy, unwholesome, vehement, venenate, veneniferous, venenous,
      venomous, vicious, violent, vitriolic