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