This dictionary gathers a list of key terms and phrases used in international justice as per the applicable international and regional legal texts: genocide, crimes against humanity, war crimes, crimes of genocide, crimes of aggression and other violations of the International Humanitarian Law. As a legal and educational tool, this book has the ambition to make accessible to all -lawyers or not, legal experts or non-experts and everyday laymen-, the sometimes "geeky" vocabulary of international justice, in order to better understand what it does and what is at stake. This dictionary also concerns the interrelated concepts of peace, sustainable development and the related notions of democracy, human rights and fundamental freedoms, rule of Law, good governance and environmental protection.