The issue of cultural categorisation causes difficulties for teachers and learners of intercultural communication as it can easily lead to stereotyping. Within applied linguistics cultural categorisation is hard to avoid; the large number of cross-cultural studies of languages and language use bear witness to this. Categorisation itself is a necessary part of human activity; without it, communication of meaning would become impossible. This article considers what happens in practice when tandem learners talk about word meaning in semi-structured conversations. Examples of moments in the conversations where interlocutors use cultural and personal categorisation are considered, as are the purposes for which they do so. Analysis reveals the wide range of such categorisation, marking both similarity and difference, fixing positions and moving on. Categorisation therefore plays a far more complex role in practice than simply limiting possibilities; in some cases, it is used to open them up. (Contains 8 notes.)