One of the objectives of the research project OncoTerm (PB98-1342) is to facilitate the translation of medical texts within the domain of Oncology by elaborating a bilingual terminological database, based on the information extracted from specialized texts as well as medical dictionaries. Medical concepts are organized in categories represented by schemas, which are systematically applied to all category members. The definitional information within each term entry is thus totally coherent with the information regarding other terms within the same conceptual category. This is conducive towards the specification of a language of terminographic definition, which is concise, consistent and applicable not only to the domain of oncology, but also extensive to other medical domains and other languages.