Despite numerous attempts by academics from many disciplines and various regional contexts, there is still no agreement on a definition of family business. Subjecting 258 definitions found in work published over the past 50 years (1964–2013) to the bibliometric techniques of consensus and co-word analysis to uncover intellectual structure, we identify the key terms used to underpin the concept of family business and to track the progress made towards consensus on its definition. We find an emergence of definitional key terms by which scholars attempt to clarify the concepts of family and family business, and growing agreement of what criteria should be met in framing a definition. This study contributes to the literature by offering a synthesis of what constitutes a family business, as well as a systematic and quantitative analysis of its evolution over a half century of research. It also shows how bibliometric tools can be used to shed light on fields where definitional ambiguity persists.