“Secession” is a commonly recognized method of state creation, yet exactly what secession entails remains a moot point. International legal instruments fail to provide any definitional and conceptual guidance; scholars adopt divergent definitional approaches, often failing to provide any reasoning to substantiate their positions. This article aims to address the important question of how to define secession in international law and relations. In order to undertake this task it develops a definition based upon etymological, conceptual and international legal principles. By doing so it makes an original contribution to existing secessionist discourses, providing a conceptual and definitional framework for the classification of secessionist state creation.