International audience The selection of terms and their harmonisation raise a number of fundamental questions in the area of terminology. These are reviewed here in the framework of the LexALP project designed to create a quadrilingual terminological database (French, German, Italian and Slovene) based on the Alpine Convention and designed to harmonise legal terminology relative to the management and preservation of the Alpine space. This paper first demonstrates that legal terminology in this context is not confined to attested legal terms but must include the legal implications of scientific, technical and even general terms. It then focuses on how the harmonisation process has a direct impact upon terminology work particularly with regard to defining concepts with precision, while at the same time mediating political implications. In conclusion, the authors underline the role played by pragmatic and institutional dimensions in the establishment of legal terminology in relation to multilingual projects.