virulent

adj

1. poisonous, venomous, envenomed, toxic, deadly, lethal, fatal; noxious, harmful, hurtful, injurious, mischievous, detrimental, deleterious, unwholesome, unhealthy; destructive, ruinous, pernicious, baleful; malignant, cancerous; (all of disease) infective, infectious, contagious, catching.

2. hostile, resentful, indignant, piqued, angry; spiteful, malicious, venomous, vicious; antagonistic, malevolent, malignant, malign, ill-disposed, rancorous; abusive, corrosive; morose, surly, sullen, moody; adverse, opposed, opposing; aggressive, warlike, belligerent, bellicose.

3. acrimonious, caustic, mordant, bitter, acrid, pungent; astringent, acerb, acerbic, severe, stern, austere, stringent; harsh, sharp, sour, acidulous, acid, tart; trenchant, keen, sarcastic, satiric, ironic, ironical; peevish, petulant, crabbed, testy, touchy, irascible, edgy; ill-tempered, ill-humored, short-tempered.