Glossary

Terms used in accessibility research and practice. Each entry has a definition, common aliases, and category tags.

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OCR(also: Optical Character Recognition): Technology that converts images of text into machine-readable text. In accessibility contexts, OCR is used by visual assistance technologies and screen readers to read printed text from photos, signs, documents, and product packaging. While valuable for blind users, OCR has…
OCR (Optical Character Recognition)(also: OCR, Optical Character Recognition, Text Recognition): A computer-vision technology that converts images of printed, handwritten, or on-screen text into machine-readable character data. OCR is foundational to a wide range of accessibility tools: extracting alt-text for image-based PDFs, reading labels for screen-reader users (e.g.,…
OSARA(also: Open Source Accessibility for the REAPER Application): An open-source extension for the REAPER digital audio workstation that significantly improves its accessibility for screen reader users. OSARA adds enhanced spoken feedback for track and item properties, transport state, mixer controls, and other DAW elements that would…
Object Localisation(also: Object Localization, Spatial Localisation): The process of determining the position and location of an object within a physical or virtual space. In accessibility, object localisation is a key challenge for blind and visually impaired users interacting with spatial interfaces, virtual environments, or graphical content.…
Object Status Recognition(also: Object State Recognition, Object Transformation Detection): The computer vision task of identifying the current condition or transformation state of objects, such as whether an ingredient is raw, chopped, sauteed, or blended. Object status recognition goes beyond simple object detection (identifying what is present) to understand how…
Object recognition(also: Object detection, Image classification): A computer vision task in which a system identifies and labels objects within images or video, often using deep learning models trained on large datasets. For blind and low-vision users, object recognition is a core capability of camera-based assistive technologies like Seeing…
Obstacle Avoidance(also: Obstacle Detection): The ability to detect and navigate around physical barriers in one's path, a critical mobility skill for blind and visually impaired people. Traditional obstacle avoidance relies on long cane techniques (sweeping the cane side to side to detect ground-level hazards) and guide…
Obstacle Detection(also: Obstacle Avoidance): Technology or techniques that identify physical barriers in a person's path and alert them in time to take corrective action. For people who are blind or visually impaired, obstacle detection systems use sensors (ultrasonic, infrared, LiDAR, or camera-based) embedded in devices…
Occupancy Grid(also: Occupancy Map, Mental Occupancy Grid): A spatial representation that divides an environment into a grid of cells, each indicating whether that location is occupied by an object, free space, or unknown. In accessibility and assistive technology, occupancy grids are used to help people with visual impairments build…
Occupational Therapist(also: OT, Occupational Therapy): An occupational therapist is a licensed healthcare professional who helps people participate in the 'occupations' of daily life — self-care, work, school, leisure, and community roles — through therapeutic activity, environmental modification, and assistive technology. In…
Occupational therapy(also: OT): A healthcare profession focused on enabling people to participate in meaningful daily activities ("occupations") despite physical, cognitive, sensory, or psychosocial challenges. Occupational therapists assess individuals' functional abilities, recommend assistive technology,…
Occupational therapy(also: OT): A healthcare profession focused on enabling people to participate in meaningful daily activities (occupations) by addressing physical, cognitive, sensory, and environmental barriers. Occupational therapists assess individual abilities, recommend and customize assistive…
Off-Screen Model(also: OSM, Virtual Buffer): A data structure maintained by screen readers that represents the content and structure of the visual display in a form that can be navigated non-visually. Traditional screen readers intercept system calls to build this off-screen model because they did not have direct access to…
Off-the-Shelf Technology(also: OTS, Commercial Off-the-Shelf, COTS): Commercially available products designed for the general consumer market without customization for specific user groups. In accessibility research, off-the-shelf technology refers to mainstream devices like smart speakers, thermostats, and lighting systems that were not designed…
Omnidirectional Camera(also: 360-Degree Camera, 360 Camera, Panoramic Camera): A camera equipped with multiple wide-angle or fish-eye lenses that captures a complete 360-degree view of its surroundings in a single shot. The resulting equirectangular image can be projected into conventional perspective views for viewing or processing. In accessibility…
Omnidirectional wheelchair(also: Holonomic wheelchair): An electric wheelchair capable of moving in any direction — forward, backward, sideways, and diagonally — as well as rotating in place, typically using Mecanum wheels or similar omnidirectional drive systems. Unlike conventional wheelchairs that can only move forward and…
On-Body Gesture(also: On-Body Interaction, Body-Based Gesture): A gesture performed on or against one's own body rather than on a device surface or in the air. Examples include tapping the thigh, swiping along the forearm, or touching the ear to trigger a command on a connected device. On-body gestures are explored as an alternative input…
On-Body Interaction(also: Body-centric interaction, Skin input, On-body input): An interaction paradigm that uses the surface of the user's own body as an input medium, typically through gestures like taps, swipes, or touches on the skin. On-body interaction leverages tactile and proprioceptive feedback from the user's own body, making it potentially…
On-Screen Keyboard(also: Virtual Keyboard, Software Keyboard, OSK): A software application that displays a visual representation of a keyboard on the computer screen, allowing users to type by selecting keys with a pointing device, head tracker, eye gaze system, or switch. On-screen keyboards are essential assistive technology for people who…
One-Handed Input(also: Single-Handed Operation, One-Handed Operation): One-handed input refers to interaction techniques and interface designs that can be operated using a single hand, accommodating users who have limited use of one limb due to amputation, hemiplegia, stroke, cerebral palsy, or other physical conditions. One-handed input methods…
Online Braille(also: Web Braille, Digital Braille, Electronic Braille): Online Braille refers to Braille content that is generated, distributed, or accessed through the Internet or digital platforms, as opposed to traditional embossed paper Braille. This includes web-based Braille translation services, downloadable Braille-formatted files such as…
Open Sound Control(also: OSC): An open, network-based protocol for communication between computers, sound synthesizers, and other multimedia devices, developed by Matthew Wright and Adrian Freed (1997). OSC sends human-readable address patterns and floating-point values over UDP/TCP, offering higher…
Open-Source Hardware(also: OSHW): Physical devices and components whose design specifications are publicly available for anyone to study, modify, distribute, and manufacture. In the assistive technology space, open-source hardware enables global sharing of device designs that communities can adapt to local needs…
Open-Vocabulary Detection(also: Open-Vocabulary Object Detection, OVD): A class of computer vision object detection models that accept arbitrary text queries at inference time rather than being restricted to a fixed set of pre-trained classes. Instead of only recognizing, for example, the 80 COCO categories, an open-vocabulary detector (such as…
OpenDyslexic(also: Open Dyslexic): A free, open-source typeface specifically designed to improve readability for people with dyslexia. The font uses heavier bottom portions on letters to help prevent visual rotation and uses unique letter shapes to reduce confusion between similar characters. However,…
OpenSCAD: An open-source, code-based 3-D computer-aided design (CAD) application that uses a scripting language to define 3-D models through constructive solid geometry operations. Unlike visual modeling tools, OpenSCAD creates models from textual descriptions of geometric primitives and…
Optacon(also: Optical-to-Tactile Converter): A historical assistive device developed in the 1970s that enabled blind people to read printed text by converting visual images of letters into tactile vibration patterns felt with the fingertip. Users would move a small camera across printed text while their other hand rested…
Optical Braille Recognition(also: OBR): A technology that uses cameras or optical sensors to detect and interpret embossed Braille characters, converting them into digital text. Optical Braille recognition works by capturing images of Braille pages and analysing the patterns of raised dots — typically by detecting…
Optical Character Recognition(also: OCR, Text Recognition): Technology that converts images of text—whether typed, handwritten, or printed—into machine-readable text data. OCR is used in accessibility to extract text from images, documents, video frames, and real-world scenes, enabling screen readers to read text that would otherwise be…
Optical Character Recognition (OCR)(also: OCR, Text Recognition): Technology that converts images of text — such as scanned documents, photographs of signs, or PDF pages stored as images — into machine-readable text that can be processed by screen readers, search engines, and other software. OCR is a critical tool for making scanned documents…
Optical Flow: A computer vision method that estimates the apparent motion of objects between consecutive video frames by tracking pixel displacement patterns. Optical flow calculates velocity vectors showing movement direction and speed across an image. In assistive technology, optical flow…
Opticon(also: Optical-to-Tactile Converter): An early assistive technology device developed by Dr. James Bliss in the 1960s that converts printed text into a tactile vibrating pattern that can be read with the fingertip. The Opticon uses a small camera to scan printed characters and reproduces them as patterns of vibrating…
Option Repertoire: A type of technology repertoire where a person has multiple tools that can each independently address the same access barrier, choosing between them based on context. For example, a person might use fidget toys, background music, or noise-canceling headphones to manage sensory…
OrCam(also: OrCam MyEye, OrCam Read): A family of wearable assistive devices made by OrCam Technologies that use a camera and on-device AI to read printed text aloud, identify faces and products, and recognize colors and banknotes for blind and low vision users. The flagship OrCam MyEye clips magnetically to the arm…
Orca(also: GNOME Orca): A free, open source screen reader for the GNOME desktop environment on Linux and Unix-like operating systems. Orca provides access to graphical applications through speech synthesis, braille output, and magnification. It uses the AT-SPI (Assistive Technology Service Provider…
Orientation and mobility(also: O&M): A professional discipline and set of skills that enable people with visual impairments to travel safely and independently through their environment. Orientation refers to understanding one's position relative to the surrounding environment using sensory cues, landmarks, and…
Orthosis(also: Orthotic, Orthotic Device, Brace): An externally applied medical device used to modify the structural and functional characteristics of the neuromuscular and skeletal system. Orthoses support, align, prevent, or correct deformities and improve the function of movable parts of the body. Common types include ankle…
Orthotics(also: Orthosis, Orthoses, Orthotic Device): Externally applied devices used to modify the structural and functional characteristics of the neuromuscular and skeletal systems — including braces, splints, and supports for the spine, limbs, hands, feet, and neck. Orthoses stabilize joints, correct alignment, redistribute…
Overlap Error(also: Key Overlap Error, Simultaneous Key Press Error): A typing error that occurs when two keys are pressed down at the same time, typically when a finger accidentally activates an adjacent key while moving toward the intended key, or when a user's hand rests on a key unintentionally. Overlap errors are particularly common among…

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