A Methodological Framework for Ontology and Multilin- gual Termontological Database Co-evolution 1 Christophe Debruyne (1), Cristian Vasquez (1), Koen Kerremans (2), Andrés Domínguez Burgos (2) (1) Semantics Technology and Applications Research Lab (STARLab), Vrije Universiteit Brussel, {chrdebru,cvasquez}@vub.ac.be (2) Centre for Special Language Studies and Communication, Erasmushogeschool Brussel, {Koen.Kerremans,Andres.Dominquez.Burgos}@ehb.be Abstract. Ontologies and Multilingual Termontology Bases (MTB) are two knowledge artifacts with different characteristics and different purposes. Ontologies are used to formally capture a shared view of the world to solve particular interoperability and reasoning tasks. MTBs are general, contain fewer types of relations and their purposes are to relate several term labels within and across different languages to cat- egories. For regions in which the multilingual aspect is vital, not only does one need an ontology for interoperability, the concepts in that ontology need to be comprehensible for everyone whose native tongue is one of the principal languages of that region. Multilinguality pro- vides also a powerful mechanism to perform ontology mapping, con- tent annotation, multilingual querying, etc. We intend to meet these challenges by linking both methods for constructing ontologies and MTBs, creating a virtuous cycle. In this paper, we present our method and tool for ontology and MTB co-evolution. Keywords: Ontology Engineering, Multilingual Termontology Bases, Ontology Evolution 1 Introduction A computer-based, shared, agreed formal conceptualization is known as an ontology. Ontologies constitute the key resources for realizing a Semantic Web. The problem is not so much what ontologies are, but how they come to be. Methods are needed to sup- port communities in reaching the meaning agreements necessary for semantic interop- erability between two or more autonomously developed information systems for a par- ticular goal. In previous work [5], we introduced a formalism for hybrid ontology en- gineering. In hybrid ontologies, concepts are both described in terms of natural lan- guage and formal descriptions. To this end, the ontologies are complemented with a glossary, containing the natural language descriptions. Just like the ontology, this glos- 1 This work was partially funded by the Brussels Institute for Research and Innovation through the Open Semantic Cloud for Brussels Project.