Nowadays, science should address societal challenges, such as ‘sustainability’, or ‘responsible research and innovation’. This emerging form of steering toward broad and generic goals involves the use of ‘big words’: encompassing concepts that are uncontested themselves, but that allow for multiple interpretations and specifications. This paper is based on the premise that big words matter in the structuring of scientific practice and it empirically traces how three ‘big words’ – ‘sustainability’, ‘responsible innovation’ and ‘valorization’ (a term closely linked to knowledge utilization) – steer research activities within a dutch research program of nanotechnology that is explicitly related to societal challenges. To do so, the theory of articulation is extended with the concept of ideographs. We report on how the top-down steering ambitions of policy are countervailed by the bottom-up dynamics and logics of researchers. We also conclude that when ‘big words’ are used in an organizational and administrative setting, it changes their effects.