In recent years, cloud computing paradigm has attracted a lot of attention from both industry and academia. However, each cloud provider uses its own techniques (languages, standards, ontologies, or models, etc.) to describe cloud services. The diversity of these techniques leads to the vendor lock-in problem, and thus, the lack of a cloud service description standardization. In addition, existing service descriptions cover only particular aspects and neglect others. For example, WSDL covers only technical aspect and does not cover business and semantic ones. Our objective is to define a standardized cloud service description that covers technical, operational, business, and semantic aspects. In this paper, we introduce different approaches that have dealt with cloud service description, and thus, we adopt USDL language as an appropriate technique to describe cloud services thanks to its expressivity by covering three perspectives (technical, operational, and business). But, USDL is still limited because it cannot cover semantic aspect and it is not intended for cloud computing domain. After that, we highlight USDL limitations that can appear in cloud computing domain and that should be taken into consideration in our research work. This paper will focus on establishing a WSMO-based ontology to define semantically cloud services. This new cloud service description is based on USDL and we will enhance it by taking into consideration some USDL limitations. Finally, we test our proposed cloud service description model on a case study to prove its applicability.