The field of Argumentation studies re-emerged in the mid-20th century, and now constitutes a welldeveloped body of sophisticated specific theories. Nevertheless, the core concepts that define the common language of these theories had never been brought together in a dictionary. In the Dictionary, argumentation is presented simultaneously as a linguistic, social and critical activity, used both to explore and to justify issues arising in ordinary life, as well as theoretical and practical issues within specialised fields. Each entry of the Dictionary provides a definition of the concept, illustrates it with one or more examples, connects it with related concepts, and shows how it can be applied. This Dictionary is intended for teachers and researchers of all communities particularly interested in argumentation studies, as well as for the open community of practitioners of argumentation in different contexts.