The purpose of this article is to establish a distinct definition of engagement for academic librarians and describe how a definition supports a clearer understanding of what is expected of librarians with engagement responsibilities. In observing a growing use of the term "engagement" over the last two decades, the authors noted how the term is frequently conflated with "outreach" and is rarely used in any discernibly distinct manner. This article traces the development and use of the term engagement in academic libraries, proposes a definition to disambiguate the term from outreach, and articulates the work of engagement for academic librarians.