Concerns about questionable patent quality are on a rise in Europe. Sound policy considerations are urgently needed to optimize the existing European patent system. Nonetheless, any meaningful policy-oriented discussion about patent quality in Europe may only start by building a strong premise and clarity about the term ‘patent quality'. However, the various meanings and perspectives attributed to patent quality show significant disharmony and patent quality is often described as ‘quality in the eyes of the beholder' rather than based on a consensual definition. At the same time, while stakeholder-perceptions on patent quality may be more subjective, academic literature gives more promising insight based on objective theories and reasoning rather than personal perspectives. In this article a broad range on literature is analyzed to answer the question; what the term "patent quality" may encompass and whether there could be one-size-fits-all definition? The paper seeks to facilitate identifying the factors that influence the quality of patents, especially from a sound policy perspective.