Science: What does nuclear deterrence mean? An active defense? Strategic defense? What constitutes a nuclear explosion? Precise definitions are critical for everything from negotiating treaties to interpretingmilitary postures of ally and adversary alike. On 20 November, the U.S. National Academies unveiled the first Chinese-English glossary of nearly 1000 nuclear-security terms.* The compendium seeks to reduce misunderstandings between China and the United States--nuclear powers that came into conflict in the Korean War and could conceivably be in confrontation again