Extremely noxious, damaging, deleterious, and disease causing (pathogenic); marked by a rapid, severe, and malignant course; poisonous.

Refers to the ability of a virus or a bacterium to cause damage to its host.

Capable of overcoming a host's defense mechanisms and causing a disease sometimes of rapid onset and severe symptoms.

Having the strength to cause disease; deadly in nature; pathogenic

c. 1400, in reference to wounds, ulcers, etc., "full of corrupt or poisonous matter," from Latin virulentus "poisonous," from virus "poison" (see virus). Figurative sense [..]

Extremely poisonous or venomous. Often applied to bacteria or a disease that can easily overcome the body's defences.

Powerful; potent.

Causing severe illness. The term is not only used in relation to viruses, but also to bacteria and other parasites.

(adj) extremely poisonous or injurious; producing venom(adj) infectious; having the ability to cause disease(adj) harsh or corrosive in tone

A disease or condition that is highly infectious or dangerous or rapidly progressing.

marked by a rapid, severe, or damaging course.

Refers to the ability of a virus or a bacterium to cause damage to its host.

able to cause disease and characterized by rapid course or severity.

Highly lethal; causing severe illness or death. [6]

describes a microorganism or virus that causes disease and that is highly infectious

(chiefly,medicine|of a disease or disease-causing agent) Highly infectious, malignant (virulent) * French: (virulent) {{trans-mid * German: (virulent),hostile