causing insidious harm or ruin; ruinous; injurious; hurtful

pernicious teachings; a pernicious lie.

deadly; fatal

a pernicious disease.

Obsolete . evil; wicked.

adjective

helpful , innocuous , kind , lovable , loving

adjective

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 , baneful , hurtful , vicious