In order to support creative design, we propose an approach composed of two methods for creating creative design ideas. The first method involves generating a candidate for a more creative design idea by focusing on the notion of 'polysemy'. The second involves evaluating the generated candidate by using a virtual thinking network. In this study, we focus on the process of synthesizing two concepts. Furthermore, we use design idea features as a substitute for the actual design idea. We attempt to create a set of design idea features that may indicate a high level of creativity. We confirmed that the estimated originality scores of all the generated candidates extrapolated the one of the base design idea.