Our purpose in this article is to analyse the practice of “pre-terminology” within a corpus ; it is interesting from this point of view because it was constructed at the frontier of the 19th and 20th centuries and was a collective work carried out by scientists and specialists: La Grande Encyclopédie . One of the initiators was the famous chemist Marcelin Berthelot. The article pertains to the emerging terminographic practice within a dictionary corpus underlain by the claim of scientific triumph and the will to spread contemporary knowledge.