Terminologists agree on a certain number of rules regarding definition writing. However, these rules are often presented as very general and informal guidelines aimed to guide terminologists. The lack of more formal rules results in problems of systematicity in specialized resources. To help fix this problem, we propose definition writing rules for terms that are semantically linked in a specialized subject field. These rules use as input the definition of a base term (for instance, to program) and the information about the semantic relationship this term holds with a second one (for instance, to reprogram means “to program once again”). Based on a previous analysis of English terms (San Martín and L’Homme 2014), this work adapts the rules defined for English to French terms and extends them to other kinds of paradigmatic relationships (near synonymy, antonymy, actantial relationships, etc.). Results show that some lexical relationships can be used to create rules that allow the generation of definitions without human intervention; for other relationships, minimal intervention is required. Finally, other relationships do not lend themselves to the automatic or semi-automatic generation of definitions.