<p>Product models are an important part of a designer’s daily practice, and as such, they require the continuous attention of design researchers for further progress in support of practice. However, how product models are described in design research, i.e., the aspects used and their structure, is undetermined, although this would provide the basis for developing and using a consistent vocabulary in a structured way. To address this problem, 101 descriptions of product models from the literature were analyzed to identify their underlying aspects. The aspects were then analyzed for statistical relations, which would indicate a structure. The analysis revealed 12 underlying aspects within the descriptions of product models and several relations within them. The identified aspects indicate a gap between the descriptions of product models and the vocabulary available for them, as there is partly no vocabulary for aspects or the existing vocabulary is not reflected in the aspects. Also, the statistical relations indicate individual logical relations between aspects, but a recurring structure in the descriptions is missing. Therefore, the findings were synthesized into a template for describing product models in engineering design research. This proposed template structures the identified aspects according to the objective of the product model description and provides a suitable term for each aspect. Thus, the underlying aspects of descriptions of product models and relations within them could be identified to provide them to design researchers in the form of a template for use during the development and further refinement of product models.</p>