virus

(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

a harmful or corrupting agency; "bigotry is a virus that must not be allowed to spread"; "the virus of jealousy is latent in everyone"

a software program capable of reproducing itself and usually capable of causing great harm to files or other programs on the same computer; "a true virus cannot spread to another computer without human assistance"