Ontology, in the sense of knowledge engineering, is nowadays one of themost promising routes for Terminology. The ontologization of terminology gave rise to the notion of ontoterminology, a terminology whose conceptual system is a formal ontology. Representing concepts explicitly and formally opens up new perspectives and is not without consequences on Terminology and its methods. The definitions of the terms in natural language are based on the definitions of the concepts in a formal language, thus achieving the degree of standardization necessary for the communication among experts, the operationalization of domain knowledge, and the exporting of terminological data in machine readable and human readable formats. Taking ancient Greek dress as knowledge domain, this paper the principles of ontologization of terminology and the tool–assisted method used for building multilingual ontoterminologies, i.e. sets of terminologies in different languages linked by means of a shared conceptual model (ontology). The tool used is a new software environment, the ontoTerminology editor (Tedi).