To ensure the re-use of domain ontologies the usual approach relies on a pivot language, e.g., Kif, intoandfromwhich the domainontologyis translated. This requires several distinct translators for the di erent target Knowledge Based System (KBS). We propose a solution which uses a unique translator whatever the target KBS, Description Logic, objects or frames. It relies on a Domain Ontology Description Language which allows writing domain ontologies in a declarative manner and a Model Ontology Description Language, a meta-language which allows a declarative description of any model based on frames, objects, relations, and Description Logic. Both languages are based on Kif binary and unary relations. Starting from these relations, we have identi ed a certain number of concepts which enable a user to performexplicitly a semantic enrichment of binary and unary relations. We introduce the concept of meta-relation which allows the expression of knowledge on the relations themselves. The se...