The Oxford Thesaurus An A-Z Dictionary of Synonyms - virulence n.

1) virulency, poisonousness, venomousness, toxicity, noxiousness, deadliness, perniciousness, injuriousness, destructiveness, malignity, malignancy, violence, balefulness: The virulence of his affliction was not recognized till it was too late. 2) virulency, acrimony, acrimoniousness, bitterness, acerbity, rancour, spleen, poison, poisonousness, venom, venomousness, malignity, malevolence, maliciousness, malice, spite, hostility, resentment, antagonism, hatred: We were taken aback by the virulence of the priest's attack on Miss Thompson's morals.