The article highlights the prominence of ism concepts in everyday and scholarly languages worldwide and presents a conceptual history and rhetorical perspective on how to study them. It also serves as an introduction to this special issue, which contributes to linguistically oriented research on political ideologies and transnational intellectual history. Although isms have gained some attention in connection with the study of ideas in history, political ideologies and theoretical discussions on analytical categories in scholarship, they have rarely been the main target of research. By focusing on the rhetorical use of ism concepts as a whole, the article directs new attention to the rhetorical potential of the use of isms in political controversies, the translation of isms and the alleged universal character of isms. The article suggests a new way of analysing political ideas, ideologies and analytical categories by applying a contextually sensitive understanding of the ism as words and their rhetorical use. It also presents an agenda for the study of isms globally.