This study explores the evolving discipline of Enterprise Architecture (EA) and the various definitions given to EA in literature and by practitioners. Due to the potential benefits, such as business and IT alignment, academics and practitioners have maintained an interest in enterprise architecture. EA has been developed outside of scientifically tested foundations, and is characterized by diversified views, seen in varied definitions given to the concept. Prior research has identified the need for conceptual strengthening as a necessity for the maturing the discipline. We contribute to this on-going discussion with a systematic literature review on the state-of-the-art of EA definitions and 26 in-depth practitioner interviews. Our study indicates that while there is still no shared definition of EA, its scope and purpose are increasingly extending from the original purpose of ITbusiness alignment towards a tool of holistic organizational design and development in the system-in-environment setting.