Do we always use the same name for the same concept? Usually not. While misunderstandings are always troublesome, they pose particularly critical problems in software projects. Requirements engineering deals intensively with reducing the number and scope of misunderstandings between software engineers and customers. Software maintenance is another important task where proper understanding of the application domain is vital. In both cases it is necessary to gain (or regain) domain knowledge from existing documents that are usually inconsistent and imprecise.

This paper proposes to reduce the risk of misunderstandings by unifying the terminology of the different stakeholders with the help of an ontology. The ontology is constructed by extracting terms and relations from existing documents. Applying text mining for ontology extraction has an unbeatable advantage compared to manual ontology extraction: Text mining detects terminology inconsistencies before they are absorbed in the ontology. In addition to this, the approach presented in this paper also introduces an explicit validation of ontology gained by text mining.