## 3 The Ambiguity of Virtual Reality Terminology in Healthcare and Beyond  
Not only in the field of VR, but also within the broader spectrum of related technologies such as augmented reality (AR) and mixed reality (MR), a significant issue arises due to the lack of consensus on definitions and the meaning of terms. Numerous authors who have explored terminology in this area point to discrepancies in the use and interpretation of terms, leading to confusion among researchers, practitioners and users, with this inconsistency also evident in the use of VR in healthcare [40; 41; 42; 43]. The lack of clarity is reflected not only in the scientific literature, but also in the definitions provided by various dictionaries [40; 43]. It also extends to the marketing of these technologies, where professional news agencies have been observed describing the same product as an example of MR, AR, and VR, and instances have been noted where companies promote their immersive  
Figure 1: Flowchart of the article search process [39]. devices in ways inconsistent with common definitions, presenting them as something they are not [41; 44]. In response to the confusion around definitions, some companies (such as _Apple_, _Cupertino_, _CA_, _USA_) strategically avoid specific terminology related to immersive technologies in their marketing and instead emphasize the use and capabilities of their technology [41; 45]. The reasons for the lack of uniform terminology can be attributed to several factors. On one hand, the rapid development of technology means that new innovations are constantly emerging, often outpacing the adoption of updated definitions [41; 43]. Some researchers suggest that this confusion arises from the exploration of VR-related concepts across diverse fields, where varying disciplinary perspectives lead to inconsistent applications of technology and thus inconsistent interpretations of the terms [41]. Cultural differences influencing the understanding of these terms and technology providers redefining terms to position their products more favorably, further contribute to the inconsistency [41; 46]. The lack of uniformity in the definitions of VR is evident in the varying criteria used: some definitions rely primarily on the hardware employed (e.g., head-mounted displays, HMDs), others on the nature of the experience (e.g., the level of immersiveness), and some on the forms of interaction [41; 43; 47; 48]. In the field of VR applications for healthcare conditions, definitions vary most significantly in how VR is characterized with respect to immersiveness. While some authors define VR as an _\"immersive experience\"_[47], _\"immersive 3D environment\"_[49] or 3D environment that differs from _\"watching an image on a typical computer or video display\"_[50], numerous studies in musculoskeletal rehabilitation report less immersive interventions. These interventions involve participants interacting with a digital environment viewed on a 2D computer screen, which is also referred to as a VR intervention [6; 51; 52; 53; 54]. Furthermore, numerous meta-analyses evaluating the effectiveness of VR include both interventions involving HMDs and 2D computer screens, such as Wii games. These analyses have been conducted in the context of low back and neck pain [32; 55], rehabilitation of orthopedic ankle injuries [34], rehabilitation following total hip arthroplasty [56], and anterior cruciate ligament (ACL) injuries [29]. Notably, meta-analysis of ACL rehabilitation by [PERSON] et al., (2024) [29] did not include any studies that examined immersive VR interventions using HMDs. This discrepancy indicates that VR in healthcare encompasses a broad spectrum of technologies and that VR remains a very broad term in this field. Such a broader understanding may also stem from some of the earliest definitions in rehabilitation from the 1990s, which did not limit VR to immersive systems but described it as including HMDs as well as other equipment such as monitors or large screens [57; 58].