Despite its centrality to most, if not all educational endeavours, what is meant by understanding is highly contested. Using Religious Education (RE) in England as a case subject this paper examines pre-service secondary school teachers' construals of understanding. It does so by employing conceptual metaphor theory to analyse their linguistic discourse. Specifically, it examines the metaphors employed by participants in a series of focus group discussions (FGD) and provides important insights into how understanding is conceptualised by these pre-service teachers who are preparing to enter the RE profession. The metaphors employed by these pre-service teachers ('understanding is SEEING'; 'understanding is CONSTRUCTING'; 'understanding is GRASPING'), focus on the dynamic and developmental nature of understanding (rather than on the outcomes) and reveal subject specific ways of thinking and practicing. This paper argues that each of the three conceptual metaphors employed by participants suggest particular ways of acting towards understanding with significant implications for teaching and learning in RE.