Virus

Part of speech: noun

Pronunciation: /ˈvaɪ.ɹəs/

Definitions

1. A microscopic infectious agent that replicates inside living cells and can cause disease in hosts
2. An infectious agent that can multiply within host cells, leading to various diseases and conditions in living organisms
3. A tiny organism that invades living cells to reproduce, which can result in illness or disrupt normal biological functions

Etymology: The Latin "vīrus" meant "poison" or "slime," and for centuries that was the whole of its job. A Roman might have used it for the venom of a snake or the foul liquid of a wound, and the sense of a liquid that spreads or infects is where the modern meaning begins. Its ancestor reaches back to an Indo-European root meaning something like "fluidity," so the word has always been about substances that move and contaminate. English borrowed the word in the Middle Ages, when it still meant poison, and it kept that sense for centuries before scientists began using it for the invisible agents of disease. Only later did it narrow to the tiny infectious particles we know today. The computer sense is a much younger development. The science fiction writer David Gerrold used "virus" in this way in his 1972 book "When HARLIE Was One," a story about a self-replicating program. The metaphor worked because a computer virus, like a biological one, copies itself and spreads through a host it does not belong to.

Synonyms: pathogen, germ, infection, microbe, contagion

Antonyms: antibody, immunity, health, wellness, cure