The words animal testing, animal experimentation, animal research, "in vitro" testing, and vivisection have similar meanings,differently. "tatiosion" means to "cut up" a living animal. It was used only in experiments that dissected live animals. The word "vivisection" is sometimes used negatively about any experiment with live animals. For example, the "Encyclopædia Britannica" described "vivisection" as: "Operation on a living animal for experimental rather than healing purposes; more broadly, all experimentation on live animals". However, dictionaries note that the wider definition is "used only by people who are opposed (dislike) to such work". The word makes people think of torture, pain, and death. People who dislike animal testing often use the word "vivisection", while scientists usually use the expression "animal experimentation" instead.