The Mapuche – Spanish parlamentos were peace assemblies held during the colonial period between the Spanish army and the Mapuche authorities in southern Chile. The interaction between these two communities led to the creation a specific political vocabulary. This article examines the occurrence of the word parlamento by addressing the two main senses attributed to it – speech and assembly/gathering – in the peace treaties of the seventeenth century. Our argument is twofold. Firstly, we contend that, over the course of the eighteen century, the latter sense imposed over the former. Secondly, we argue that, during the same period, the word entered the political vocabulary of the interaction modalities between the Spanish Crown and the Chilean Mapuche. Drawing both on socio-historical and discursive approaches and on terminology concepts and tools, this article examines the thematic trajectory of the word parlamento and its network of meanings, as well as that of other words that referred to the actors and the physical settings where said assemblies took place. Hence, by analyzing a particular case of translation equivalence, it aims to contribute to the history of translation, general history, as well as to the history of political concepts.