This chapter presents the Multi-Paradigm Modelling for Cyber-Physical Systems (MPM4CPS) ontology. This ontology integrates the Shared, MPM and CPS ontologies respectively introduced in Chapters 2, 3 and 4. It includes cross-cutting notions such as viewpoints, model-based development processes and modelling paradigms that together relate the formalisms and workflows (and their paradigms) to the part of CPSs developed with these formalisms. A brief state of the art on these notions is first presented, on which the MPM4CPS ontology builds. An overview of the ontology is then developed by introducing its main classes and properties. The validation of the ontology is finally presented by showing how it can adequately model the two case studies briefly introduced in Chapter 2. The chapter also discusses perspectives and future work on this integrated ontological framework, which can serve as a basis to develop model management solutions to relate and combine modelling languages and tools, in order to better develop cyber-physical systems with appropriate formalismes and workflows.