Large and complex enterprise systems face the same kind of information processing problems that exist on the web in general, and constructing an ontology is a crucial part of many solutions. Construction of enterprise ontologies needs to be at least semi-automatic in order to reduce the effort required, and another important issue is to introduce further knowledge reuse in the process. In order to realise these ideas the proposed research focuses on semi-automatic ontology construction, based on the methodology of case-based reasoning.