This paper sheds light on an integral aspect of the global energy system: energy security. Energy security is a universal topic that shapes policies and regulations in order to achieve higher levels of energy security and thus provides societies with a better life. Understanding the concept and its implications requires a holistic definition, but current research literature lacks a commonly accepted, precisely defined definition. Therefore, the research gap is the absence of a comprehensive definition that takes into account all energy security dimensions, and the absence of well-studied relationships between energy security and its dimensions. Taking that in mind, the gap is addressed by a systematic review of energy security definitions and by building a structural dimensionalization of energy security. Thus, this review aims to track changing definitions of energy security in modern times and formulate a concise and comprehensive definition. Furthermore, using a structural approach, 15 dimensions, and related parameters of energy security are determined and categorized to illustrate the range of issues covered by the term and to enable precise evaluation of the energy security of energy systems. The results of this review show clearly how energy security could be defined generically to account all dimensions, and show the relationships between these 15 dimensions and energy security. Understanding all dimensions of energy security provides insights for policymakers to formulate policies that account for all of these dimensions.