1. (a.) Extremely poisonous or venomous; very noxious or injurious\.

2. (a.) Very bitter in enmity; actuated by a desire to injure; malignant; as, a virulent invective.

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