Based on a 2010-11 study involving senior researchers from seven disciplines, this article explores critically some of the diverse interpretations of impact in different disciplines, sub-fields and modes of research, and researchers' views about how these interpretations articulate with top-down impact agendas and with university structures and incentive systems. Among the participants in the study, humanities researchers referred more explicitly to disciplines in framing their definitions of impact; social researchers, to theoretical and methodological traditions of research; and physical scientists, to modes of research (such as applied and theoretical). The article highlights the limits of unidirectional and short-term notions of impact and of pressures to demonstrate chain-link trajectories of influence from research insights to non-academic changes and benefits. Nonetheless, it argues that the current context offers an important (though easy-to-miss) opportunity to debate and reconceptualise "impact" and its relevance to accountability processes, and to re-calibrate assessment methodologies.