Gestalt
The simple word gestalt meaning shape or form was imported into twentieth century English to provide a more specialised term in psychology and design. Due to the way the human mind processes information, people generally more readily perceive an overall image rather than the component parts, and this is often illustrated with figure-ground image illusions such as the vase and figures one shown here. In everyday English gestalt can now be used to describe the overall quality or character of something, where that is far more than the sum of the individual parts.
For a fascinating illustrated discussion of the use of Gestalt in design terminology and its translation into plain English, there is an extensive article at Smashing Design and also an informative German etymology.