malignant -
adj. 1 a (of a disease) very virulent or infectious (
malignant cholera). b (of a tumour) tending to invade normal tissue and recur after removal; cancerous.
2 harmful; feeling or showing
intense ill will.
malignant pustule a form of anthrax.
malignancy n. (pl. -ies). malignantly adv. [LL malignare (as MALIGN)]