virulent
vir-u-lent
adjective
Extremely infectious, poisonous, or harmful, especially regarding diseases or toxins.
"The new flu strain proved highly virulent."
adjective
Bitterly hostile, malicious, or intensely unpleasant in expression or feeling.
"He launched a virulent attack on his critics."
Thesaurus
Synonyms: acerb, sulphurous, vitriolic, unpleasant, blistering, acrid, caustic, acerbic, sulfurous, bitter, acid, toxic
Antonyms: avirulent