Among the many possible goals that instructors have for students in general chemistry, the idea that they will better understand the conceptual underpinnings of the science is certainly important. Nonetheless, identifying with clarity what exemplifies student success at achieving this goal is hindered by the challenge of clearly articulating what conceptual understanding entails. While this may be a case of “we know it when we see it”, the design of assessments ultimately requires a specific definition of conceptual understanding. Without such a specific definition of the construct, it may be readily argued that a proposed measure does not provide evidence about, in this case, conceptual understanding because the construct itself is insufficiently identified. Given the wide range of possible definitions, the availability of empirical data about instructor perceptions of the meaning of conceptual understanding can play an important role in constructing a definition that meets the broadest possible needs of the chemistry education community. Thus, with the aid of roughly 1,400 instructor written definitions, a consensus articulation of conceptual understanding is identified in this work.