Elasticity is a key distinguishing feature of cloud services. It represents the power to dynamically reconfigure resources to adapt to varying resource requirements. However, the implementation of such feature has reached a level of complexity since various and non standard interfaces are provided to deal with cloud resources. To alleviate this, we believe that elasticity features should be provided at resource description level. In this paper, we propose a Cloud Resource Description Model (cRDM) based on State Machine formalism. This novel abstraction allows representing cloud resources while considering their elasticity behavior over the time. Our prototype implementation shows the feasibly and experiments illustrate the productivity and expressiveness of our cRDM model in comparison to traditional solutions.