WordWeb Online

1. Extremely poisonous or injurious; producing venom
   "a virulent insect bite"
   - deadly, venomous
    
2. Infectious; having the ability to cause disease
    
3. Harsh or corrosive in tone
   - acerb, acerbic, acid, acrid, bitter, blistering, caustic, sulfurous [N. Amer], sulphurous [Brit, Cdn], vitriolic, sulphureous [Brit]

See also: deadly, highly infective, toxic, unpleasant, virulence, virulency, virulently

Antonym: avirulent

Encyclopedia: Virulent