“What do scientists mean when they talk of a virus? This is not quite so elementary as some people might believe. In The Shorter Oxford English Dictionary, a virus is defined as "a morbid principle, or a poisonous venom, especially one capable of being introduced into another person or animal." The dictionary takes its cue from the Latin virus, which denotes a slimy liquid, a poison, an offensive odor or taste. It is a colorful definition, redolent of medieval notions of disease origins in evil emanations, but it offers little by way of scientific understanding.”