pernicious

Synonyms: baleful damaging dangerous deadly deleterious destructive detrimental devastating evil fatal harmful iniquitous injurious killing lethal maleficent malevolent malicious malign malignant miasmatic miasmic mortal nefarious noisome noxious offensive pestiferous pestilent pestilential poisonous prejudicial ruinous sinister toxic venomous virulent wicked

Antonyms: helpful innocuous kind lovable loving