Today, the development of a VR application is still a long and difficult task as new features are being developed for Virtual Reality. There is a need to have better modelling tools which will help the designer to model the VR application much more from the domain expert point of view by involving him more in the design process. In this paper, a new approach is introduced for designing and developing a VR application where the domain expertise is used for generating it more easily. This approach uses ontologies as a way of grasping the knowledge of a domain, expressing the virtual world much more in terms of the end-user domain, generating the virtual world more easily and performing intelligent reasoning. Furthermore, ontologies are also used as a conceptual modelling tool allowing a non-VR-skilled person to model his VR application using the concepts of Virtual Reality more intuitively and more oriented towards his domain expertise.