Standard middleware platforms are unable to cope with extreme heterogeneity and dynamicity of distributed systems. With new trends in mobile/pervasive applications, distributed systems are required to connect to one another at run time, implying that heterogeneities arising in systems need to be resolved on the fly. This ability of a system to interact with a different system is known as interoperability. More advanced solutions, which exceed the state-of-the-art in middleware, are required to handle interoperability on the fly. This paper investigates the challenges of enabling dynamic interoperability for the domain of vehicular ad-hoc networks (VANETs). The paper uses semantic web technologies to help devise an emergent middleware to enable different VANETs to interact with each other at runtime. An ontology-based framework coupled with an experimental evaluation of the framework is presented. The need for linguistic techniques in assisting ontologies is also emphasized in the framework.