Objectives: There has been significant advancement in virtual reality (VR) technology since its conception in 1960, and this evolution has particularly accelerated in recent years. Alongside this, we are seeing an expansion of research interest within which the definitions and nomenclature can be complex and lead to potential misunderstanding or confusion. We present a systematic review of definitions of the term VR as reported within the medical literature with the aim to establish the terminology used to define VR, the differences that exist through the literature, and if they have changed over time. Methods: By reporting according to the PRISMA guidelines, we present a systematic review of VR definitions in the English language medical literature. The databases Medline, PubMed, Web of Science, and Scopus were searched using the search terms ‘virtual reality’, ‘definition’, ‘defined’, or ‘define’. Articles were included if they were peer-reviewed, within the medical literature, published between 22nd December 2001 and 22nd December 2021, and offered either an original or cited definition for the term VR. Following data extraction, quantitative analysis of terminology over time and term density maps have been created. Results: Eighty-eight studies were included offering 105 definitions of the term VR. Of these articles, 58 were published within the last 5 years. Common terms when defining VR included ‘computer’, ‘environment’, ‘user’, ‘interactive’ and ‘simulation’. In recent years, a novel term ‘head mounted display’ has emerged which was not previously featured in healthcare literature. Conclusions: This systematic review highlights that the published literature in the field of VR is rapidly expanding. With the growth in technology we can see a complex network of terminology emerge with little homogeneity. Definitions of VR are numerable and high variability exists. We recommend the requirement for consensus in order to urgently unify terminology within the immersive technology field, and whilst waiting for agreement, an evidence-based definition for VR has been suggested. Public interest summary: A systematic review of the literature has been performed to better understand the terminology that academic authors have used to define what virtual reality technology is. This review concluded that a wide range of definitions have been used in the last 20 years. Throughout these definitions a large number of individual terms are being used with very little agreement on their appropriate use. With rapidly expanding technology and increasing complexity within the terminology, future research is at risk of misrepresentation until the academic community agree on the most appropriate terminology to be used when defining VR.