The modern phenomenon of cybercrime raises issues and challenges on a scale that has few precedents. A particular central concern is that of establishing clarity about the conceptualization of cybercrime and its growing economic cost to society. A further related concern is focused on developing appropriate legal and policy responses in a context where crime transcends national jurisdictions and physical boundaries. Both are predicated on a better understanding of cybercrime. Efforts at defining and classifying cybercrime by the use of taxonomies to date have largely been descriptive with resulting ambiguities. This paper contributes a semi-formal approach to the development of a taxonomy for cybercrime and offers the conceptual language and accompanying constraints with which to describe cybercrime examples. The approach uses the ontology development platform, Protégé and the Unified Modeling Language (UML) to present an initial taxonomy for cybercrime that goes beyond the descriptive accounts previously offered. The taxonomy is illustrated with examples of cybercrimes both documented in the Protégé toolset and also using UML.