The remarkably growing body of academic literature on the university in relation to sustainability pivots around the idea that the university has an important role to play regarding this issue. However, which role this precisely is and what type of university this requires is often left implicit. This article presents an empirical analysis of how the idea of the "sustainable university" -- understood as any notions of an existing or desirable future university that engages with sustainability -- is discursively constructed in 4584 scientific publications on the topic. Through a combination of a discourse analysis with the content analysis tool topic modelling, three discourses on the sustainable university are discerned: the sustainable higher education institution, the engaged community, and the green-tech campus, providing the groundwork for further research and debate on what the sustainable university could be and should be.