virus

1. A submicroscopic, non-cellular structure that consists of a core of DNA or RNA surrounded by a protein coat, that requires a living host cell to replicate, and that sometimes causes disease in the host organism (such agents are often classed as nonliving infectious particles and less often as microorganisms). (countable, uncountable)
2. A species thereof. (countable, uncountable) · Meronym: virion (individual particle)· Some viruses, such as norovirus, cause sporadic outbreaks of gastroenteritis.
3. An individual particle thereof: synonym of virion. (countable, uncountable) · Under electron microscopy, a few viruses were seen floating near the cells.
4. A quantity of such infectious agents, considered en masse. (uncountable) · Not much virus was detectable on a nucleic acid test; the viral load was very low.
5. A disease caused by such an infectious agent; a viral illness. (countable, informal, uncountable) · He's got a virus and had to stay home from school.
6. A type of malware which can covertly transmit itself between computers via networks (especially the Internet) or removable storage such as disks by inserting its code into other executable files, often causing damage to systems and data; also computer virus. (countable, uncountable)
7. Any type of malware. (countable, uncountable)
8. Any malicious or dangerous entity that spreads from one place or person to another. (countable, figuratively, uncountable)

Plural viruses