viru-, vir-

1. That which is very infectious, malignant, or poisonous.
2. Descriptive of being capable of causing disease by breaking down protective mechanisms of the host.
3. Bitterly hostile or antagonistic; hateful: "He received virulent criticism from his supervisor."
4. A reference to being intensely irritating, obnoxious, or harsh.

1. Conveying or producing a virus or other noxious agent.
2. A description of an organism that contains or carries a virus.

To fly through the mouths of men.

An alternate translation: "To spread like wildfire." The allusion refers to gossip, rumor, and news.

1. A submicroscopic parasitic particle of a nucleic acid surrounded by protein that can only replicate within a host cell.

Viruses are not considered to be independent living organisms.

2. A computer program that is part of another program and inserts copies of itself, often damaging the integrity of stored data.

It travels with the program that contains it.

3. Etymology: "venomous substance", from Latin virus, "poison, sap of plants, slimy liquid".

Small living particles which can infect cells and change how the cells function.

Infection with a virus can cause a person to develop symptoms; so that, the disease and symptoms which are caused depend on the type of virus and the type of cells that are infected.

No organism is safe because viruses today infect every organism on earth, and sometimes even other viruses.

Because viruses do not leave fossils, it has been hard for researchers to track down their evolutionary history; consequently, much of our understanding of the history of viruses is based on their genetics.