To be snarky, service design literally means the design of services. 

Services are essentially experiences, where something of value is provided, which may or may not be tangible. 

Experiences can involve some or all people, behaviours, processes, technology and interactions with tools, digital or otherwise. These represent a palette to design with and choreograph end-to-end experiences optimistically with the goal of integrating disparate tasks, reducing friction, improving customer delight and the like. 

Services are often provided through the building of new and existing relationships, through companies with brands that make promises . . . In this way, service design is also helping companies make and keep their brand promises. 

Often, if you are developing service design in new or deep ways within a company, you will eventually bump into organizational development issues, as roles may need to change and structures alter to accomplish the service goals.

Chicago, United States
Managing Partner at Insitum