This contribution describes some important principles that should be used when establishing terminological ontologies, and demonstrates that these principles may be used both for terminological ontologies, i.e. domain-specific ontologies, and for general language ontologies such as WordNet. In doing this, the paper argues that the principles for building ontologies should not allow indeterminacy in the resulting ontologies. The principles described here have been developed in the research and development project CAOS – Computer-Aided Ontology Structuring. CAOS is a joint research project carried out by Bodil Nistrup Madsen, Hanne Erdman Thomsen and Carl Vikner, Department of Computational Linguistics, Copenhagen Business School. The descriptions of the principles of CAOS and the examples used originate from joint papers.