Design ideas are commonly used as an indicator of success of design methods and processes. Yet it is very rarely defined what precisely constitutes "an idea", and how such an idea manifests itself to the researcher. This paper presents an examination of design idea definitions based on a thorough study of 75 research contributions. We construct a typology of seven definitions of design ideas. The purpose of the typology is to offer shared definitions and descriptions of design ideas to design and creativity researchers, aiding a higher degree of specificity when studying and analyzing the emergence of ideas in design processes.