With the advent of Cloud Computing, organizations are increasingly migrating their information and communication technology (ICT) resources to the cloud. This has recently gained a great attention because of cloud pay-as-you-go model which drastically reduces actual IT infrastructure with high performance and continuous availability. In order to effectively utilize existing cloud resources, organizations may look for available cloud resources from different cloud providers. However, cloud resources are heterogeneous and described by different standards which prevents an easy and dynamic interoperability between organizations. In this paper, we propose a semantic framework tackling this heterogeneity issue. We develop a set of ontologies to semantically represent cloud resources by looking at three cloud resource description standards: Topology and Orchestration Specification for Cloud Applications (TOSCA), Open Cloud Computing Interface (OCCI), and Cloud Infrastructure Management Interface (CIMI). Hence, our framework promotes the creation of a common semantic knowledge base of cloud resources described using these different standards. This knowledge base allows a seamless translation of cloud providers' resource descriptions. We developed an application to validate our approach as a proof of concept. We also evaluated the feasibility and completeness of our semantic framework on use cases obtained from standard specifications