(a.) Having poisonous qualities; deadly; destructive; injurious; noxious; pernicious\.

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