Following are the definitions as per self understanding, Can comment/mail me for corrections.
Cloud Computing: Its a technology shift of software application installation, storage, processing on to the servers which is located remotely in the internet and not on to your private computer.
This simplifies many thinks like license management, Working from home, code security, etc.
Following are well know companies working on
SDN : Software-Defined Networking :This is the centralized approach that simplify in bring the computer networking functionality/processing to controller which is called as SDN controller.
SDN enables users to program network layers, separating the data plane from the control plane
NFV : Network Functions Virtualiztion