The authoritative source for VR & AR definitions: the xR Glossary & xR Dictionary of Acronyms.

Tracking capability wherein both a headset and associated controllers mapped to users’ hands are tracked in a room scale space especially as opposed to static, solely rotational tracking (3 DoF) or partial room scale, where the head-mounted unit is tracked in space, but controller inputs are not (6.3 DoF).
8K resolution or 8K UHD is the current highest ultra high definition television (UHDTV) resolution in digital television and digital cinematography. 8K refers to the horizontal resolution in the order of 8,000 pixels.
A method of addressing individual LCD elements that provides faster update timing, better color and a wider viewing angle than passive-matrix displays.
The addition of computer-generated imagery (CGI) to real life imagery, in either a see-through or video-based display. Generally, the CGI is registered to the real world through the use of a variety of sensors. These sensors may include video, GPS, and external or internal tracking systems. See Mixed Reality.
A display system that provides a stereo 3-dimensional image without the use of eyewear.

Amount of light emitted by a display, either via projection, illuminated pixels, or a backlight component. The brightness of a traditional emissive panel is measured in “nits” (a function of candelas per square meter), and in projection-based technology in ANSI (American National Standards Institute) Lumens.
Ratio figure which describes the maximum brightness a display is capable of achieving relative to its maximum darkness. Measurement is typically measured under highly controlled conditions by manufacturers. While it is a measure closely related to brightness in displays, it currently has no universally standardized or agreed upon measurement / evaluative methodology.
Room-sized display system comprised of three to six walls. Often built with stereo-optic displays. Typically images are projected, but systems can also be built from video display panels. Sizes are typically 3-4 meters on each side. Valued for collaboration in virtual environments. First demonstrated by the University of Illinois, Chicago in early 1990’s.
Cylindrical projection surface.  Typically, 3 meter or greater diameter. Provides a seamless 360° visual field and can show stereo imagery. Useful for groups. A more compact form factor than a dome.
Semi-spherical projection surface.  Typically, 3 meter or greater diameter. Provides  a seamless 360° visual field and can show stereo imagery. Useful for collaborative work.
A display that emits light, as opposed to a display that reflects light. Paper is a reflective display. Television is an emissive display. Most computer displays not using projectors are emissive.
Entertainment Centers are facilities with a wide vari[1] ety of entertainment experiences or systems within a single out-of-home entertainment center or FEC, much like a small indoor amusement park. These locations are not dedicated to a specific type of experience can house entertainment experiences ranging bowling to gaming arcade cabinets to slot machines.
The use of specialized hardware positioned towards a display’s user to record the orientation and activity of the eyes. Distinct from “gaze-based” tracking (which often refers to IMU-driven 3 DoF rotational tracking, which follows the orientation of a user’s head), eye-tracking is measured independent of the rest of the head, and can be used to supplement of replace other forms of tracking or input, especially in service of goals related to accessibility.
A family entertainment center is an entertainment center that is marketed towards families  See Entertainment Center.
A horizontal measurement of image size, typically measured in degrees. A 180° field of view encompasses half of a circle.
A system that provides a simulation of resistant or active forces to parts of the body. Often called force feedback.
A form of discrete or integrated processing component specifically designed to perform graphical rendering tasks, as opposed to a traditional processor. Required to operate a tethered HMD.
A display that provides proprioceptive stimulation to the user. This includes force and tactile displays.
A device, which is fastened to the head, and used to display a computer-generated scene. A Head Mounted Display typically provides a stereo-optic (3D) view through the use of two displays placed directly in front of the eyes. Typically, HMDs include a tracking device to convey the direction of gaze to the graphics engine.
A display presented in the line of sight of the user, which overlays computer generated information over the real world by presenting it on a transparent display surface. A HUD may present Augmented Reality but it also may present data that is not registered to the environment. Typical applications are in vehicles and near-eye displays. Non-AR data often includes vehicle status data (speed, orientation, navigation, systems status, etc.), text or graphic information used for maintenance, and manuals and other information regarding specific tasks.
Large, flat-screen display panel, used individually, or as a sub-display in a video wall. Often used to provide stereo-optic display.
Refers to various forms of entertainment in destination locations and specialized venues, such as amusement parks and entertainment centers. LBE is comprised of des a wide variety of experiences offering various levels of immersion and sometimes can incorporate multiple participants simultaneously.
A display using an array of long, narrow lenses placed side by side and which are placed over a multiplexed display image in such a way that each eye receives a different, parallax-adjusted image. Lenticular displays are common as novelties that provide changing or stereoscopic images printed on paper. They have also been used with active displays to provide stereoscopic images. In such displays, the lenses are placed vertically, and the display behind them consists of pairs of right-left slices of the complete image.
A display that fills a space with focused light, creating an image in space. Projected holograms are one type of lightfield display. Light field display make use of multiple dimensions of light, as created or captured by specialized devices. Lightfield displays make use of the plenoptic illumination function to express an image of a scene from any possible viewing position at any viewing angle.
A display technology consisting of triads of Red, Green, and Blue liquid crystals. Used in many displays across a wide variety of form factors, including phones, laptop computers,  HMDs, projectors and LFDs. LCD displays require a backlight.
A display using LEDs for the lightsource behind an LCD display panel. This has succeeded fluorescent lighting sources , and is preferred for its lower power requirement and more even light distribution.
The addition of computer-generated imagery to real life imagery, either in a see-through or video-based display. See Augmented Reality, the preferred descriptive term.

Note: This is primarily a marketing term put into common use by Microsoft in 2018.
A type of VR HMD characterized by its reliance on a smartphone to display, control, and store VR or AR content. The most common example is Google Cardboard.
A form of brain-computer interaction which typically employs electroencephalography (EEG) readings using non-invasive sensors to determine user intent in certain immersive display applications.
The use of specialty chemicals/agents to reproduce specific scents, usually in an immersive/experiential capacity.
An LED technology that adds an organic emissive electroluminescent layer to the LED.  This reduces the component count in a display be combining the display and lighting in one module. OLEDs can provide higher contrast than LCD/LED panels.
A direct measure of the number of pixels per 1 in². This is sometimes referred to as Points or pixels per inch (PPI) or dots per inch (DPI).
Direct measure of the width and height dimensions of a rectangular display, in pixel width by pixel length. This is often referred to as display resolution.
Amount of space between dot clusters on an emissive large format display, most often discussed within the context of optimal viewing distances. This specification is analogous to pixels-per-inch but is primarily used for larger form factors, such as digital signage.
Semiconductor nanocrystals which can produce pure monochromatic red, green, and blue light. LED displays built with quantum dot technology (QLED) entered the marketplace in the mid-20-teens. This technology may replace LED and OLED displays, due to QLED’s physical flexibility, wide color gamut, high color purity, high brightness with low turn-on voltage, and ultrathin form factor. It is possible to build transparent displays using QLED technology.
A 3D rendering technique which traces the paths travelled by light in a scene and simulates their interaction with surfaces, enabling highly accurate and photorealistic reflections, shadows, and other visual effects, at significant cost to computing load and rendering time.
The number of times an image display changes, measured in hertz. A faster refresh rate results in smoother animation, and reduces motion artifacts in the image.
The physical dimensions of a rectangular display, usually measured in inches or meters, often as a single diagonal figure.
A class of headworn AR display device in the form factor of traditional eyeglasses.
Sound that comes from, or is perceived to come from, a sphere around the listener. Sometimes referred to as 3D sound.
Standalone VR
Entirely self-contained VR hardware with no tether or removable computer or display components.
A group of complex computational tasks which constructs or updates a map of an unknown environment while simultaneously keeping track of an agent's location within it. This is used for tracking by inside-out HMDs and augmented reality applications.
A flat display that provides the illusion of depth by providing slightly different images to each of the viewer’s eyes, enabling the brain’s understanding of parallax to create a 3-dimensional visual perception. There are several methods of 3D illusion, including using active glasses that alternately obscure vision on each eye (shutter glasses), using polarized light to separate right and left images, and using different colored lenses (anaglyph) to provide separate images to each eye.
A specialized form of computer processor manufactured for use in compact electronic devices such as smartphones, named for its inclusion of several different computing systems, including CPU, GPU, I/O, Networking, and Security.
A system that provides a sense of touch, such as temperature, friction, texture, etc.
An array of traditional hardware using any given display technology (including those not commonly found in consumer-grade displays, such as laser projection) but designed with particular attention to thickness and bezel size, in order to give the impression of a single, large display.
An AR system comprised of a display with a camera facing the viewer. The software reverses the image to create a mirror image, as opposed to a TV-like image. Virtual mirrors are popular in retail environments.
A synthetic environment comprised of computer-generated, three-dimensional objects with which random interaction is possible. An experience may be considered Virtual Reality (VR) if it meets these three criteria:
  • VR is an interactive experience created and mediated by a computer.
  • VR is comprised of worlds which are made up of 3D objects.
  • VR provides random interactivity.
A computer-based simulation displayed as graphics. See Virtual Reality.
A display that provides three-dimensional images that occupy real 3D space and may be viewed from any angle. There are a number of ways to create real or apparent volumetric displays, including multi-planar displays, holographic displays, lightfield displays, and spinning display surfaces.
Broadly describes any structure which guides waves of energy, as in acoustics or electromagnetism. Within xR, waveguides represent a complex component commonly employed in the construction of transparent displays for fixed and near-eye augmented reality displays.1
A general term to indicate any of Augmented, Mixed, or Virtual Reality.

Two dimensional.
Three dimensional.
Third Generation. Often describing the third generation of cell-phone technology.
Four dimensional. Usually refers to the three spatial dimensions plus time. Also infers animated or moving 3D images.
A display and television standard of approximately twice as many pixels as HDTV (see).
A wireless networking standard, typically called WiFi (Wireless Fidelity). Common varieties include A, B, G, N, and AC. Connections may be open or encrypted.

WiFi is typically used in homes, commercial establishments, and in public spaces, as it provides connections at a distance of up to 100 meters. Many devices connect to WiFi, including computers, mobile devices, printers, and cameras.
A display and television standard of approximately four times as many pixels as HDTV (see).
Association for Computing Machinery. Sponsor of many computer and computer graphics conferences, including SIGGRAPH. (Special Interest Group; Graphics.
Accelerated Graphics Port. A bus used to connect image generators in personal computers.
American National Standards Institute.
Augmented reality.
Advanced Research Projects Agency. Formerly DARPA (DefenseARPA). US DoD agency responsible for funding advanced research projects in many areas. Now again called DARPA (see)
Army Research Lab (US). Headquartered in Adelphi, MD. 
Air Traffic Control.

Close Combat Tactical Trainer. US Army second generation virtual trainer. See SIMNET.
Computer Graphics/Computer Graphics Imagery.
Computer Human Interface. ACM group conference on the discipline is SIGCHI.
Central Processing Unit. The core logic/processing unit of a computer.
Cathode Ray Tube. The largely obsolete display component of TVs and computer monitors prior to the 2000's.
Defense Advanced Research Projects Agency. Formerly ARPA (see). US DoD agency responsible for funding advanced research projects in many areas.
Distributed Interactive Simulation. Communication protocol for military simulations developed in the 1990's.
Department of Defense (USA).
Degrees Of Freedom. Used to discuss motion and tracking capabilities.
Defense Modeling and Simulation Coordination Office
Digital Signal Processor. Used to process sound, video, and other signal data.
Electronic Frontiers Foundation. A group lobbying and working for freedom for electronic communications equivalent to that of other forms of communication.
European Space Agency. The European Union's equivalent to the United State' NASA.
Federal Aviation Administration (US).
Federal Communications Commission (US).
Finite Element Analysis.
Force Feedback. Also known as a force display.
Floating Point Operations Per Second. A measure of computing speed. Often, MFLOPS, GFLOPS, or TFLOPS (Mega-, Giga-, Tera-FLOPS)
Field of View. A characteristic measurement of display system image size.
Frames per Second. A measure of computing and display performance.
GigaByte. One billion bytes, or characters. A measurement of memory and storage capacity.
Geographical Information Systems. Computerized maps and related programs and databases.
Graphics Language. A standard for specifying 3D objects for computer display.
High Definition Television. A standard for broadcast television, often used to describe display system pixel density. True HDTV provides 1920 horizontal pixels and 1020 vertical pixels, for a total of 2,073,600 pixels. (Also called 2K TV – the approximate number of horizontal pixels.)

Newer versions of displays are described as multiples of HDTV. 4K TV provides approximately twice as many Pixels. 8K TV provides roughly four times as many pixels.
Human Factors.
Human Interface Technology Laboratory (HITL), at the University of Washington in Seattle, USA. A pioneer location for xR.
High-level Architecture. A networked simulation standard used primarily in military simulation. Superceded DIS and SIMNET.
Head Mounted Display. Also, headset, goggles.
Head-Up Display. A display shown on a transparent surface that allows data to be superimposed on a view of the real world. Typically not attached to the viewer, such as part of an vehicle dashboard.
Hertz, cycles per second.
Institute of Electrical and Electronics Engineer. An internationally-recognized standards-setting organization.
Institute for Simulation and Training, Orlando, Florida, USA. A program of the University of Central Florida (UCF).
Johnson Space Center, NASA's Houston, Texas, USA headquarters.
Jet Propulsion Laboratory, NASA facility based in Pasadena, California (USA).
Location Based Entertainment.
Liquid Crystal Display.
Light Emitting Diode.
Modeling and Simulation.
Megahertz: I million cycles per second.
Musical Instrument Digital Interface. A technology for controlling instruments, and other devices by computer.
Millions of Instructions Per Second. A measure of computing speed and power.
Massachusetts Institute of Technology. 
Ministry of Defense.
Motion Pictures Expert Group, A standards setting organization. Deals with the coding of multimedia information. Also MP3, MP4, variations of the original MPEG standard.
National Aeronautics and Space Agency (USA).
National Science Foundation (USA).
Naval Postgraduate School (USA). Located in Monterrey, Califonia.
Organic Light-Emitting Diode. A flat, flexible display technology.
Picture Element. The basic building block of a graphic display, and the unit in which display resolution is usually expressed.
Polygons, the basic building blocks of 3D models. Graphics performance for VR is sometimes expressed in Polys per second.
Point Of View.
Research and development.
Society for Computer Simulation.
Special Interest Group, Graphics. A sub-group of ACM (see). Also, the annual conference of the same name.
Simulation Networking. A demonstration project and training system of the US DoD, Army and ARPA developed in the mid-1990's.
Program Executive Office for Simulation, Training and Instrumentation. US Army program for simulation and training.
Terabyte: One trillion bytes, or characters. A measurement of memory and storage capacity.
Tactile Feedback. Also referred to as tactile displays.
Universal Serial Bus. A fast serial bus used in personal computers. For connecting external peripherals. Successor to RS-232 standard for serial data transmission.
A computer operating system, originally developed by AT&T. Predecessor to LINUX, which is open source.
Visual simulation.
Virtual Reality, Virtual Environments, Virtual Worlds. Collectively, xR (see).
A collective term for augmented, virtual, and mixed reality. Note that the "x" is lower case, denoting an unknown variable.