Meaning

noun (virology) ultramicroscopic infectious agent that replicates itself only within cells of living hosts; many are pathogenic; a piece of nucleic acid (DNA or RNA) wrapped in a thin coat of protein

noun a harmful or corrupting agency

noun a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer

originFrom Middle English virus, from Latin vīrus (“poison, slime, venom”), via rhotacism from Proto-Italic *weizos, from Proto-Indo-European *wisós (“fluidity, slime, poison”). First use in the computer context by David Gerrold in his 1972 book When HARLIE Was One.

Etymology from Wiktionary, CC BY-SA 3.0