Glossary

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Aided AAC(also: Aided Augmentative and Alternative Communication)

The branch of Augmentative and Alternative Communication that relies on an external tool to produce or carry the message — ranging from low-tech paper communication boards and picture-exchange cards to high-tech tablet apps and dedicated speech-generating devices accessed via…

Aided Language Stimulation(also: Aided Language Modeling, Aided Language Input, ALgS)

A communication intervention technique in which a conversation partner models language on an AAC device while speaking, pointing to symbols on the learner's communication system as they talk. This includes describing their own actions, narrating the learner's actions, providing…

Aim Assist(also: Aim Assistance, Auto-Aim, Bullet Magnetism)

A category of input-assistance features in shooter games that help a player acquire or track targets, for example by enlarging the effective cursor area, bending projectile paths toward enemies, or slowing the aim reticle when it is near a target. Aim assist is widely used to…

Aira

A visual assistance service that connects blind and low vision users with trained human agents who provide real-time visual information through a smartphone camera or smart glasses. Unlike AI-only solutions, Aira agents can answer complex questions, provide nuanced descriptions,…

Airport Accessibility

The practices, technologies, policies, and physical design choices that enable travelers with disabilities to use airports independently and with dignity. In the United States, airport accessibility is governed partly by the FAA's Airport Disability Compliance Program (AC…

Akinesia(also: Poverty of Movement)

The loss or impairment of the ability to initiate voluntary movement, distinct from muscle weakness or paralysis. In Parkinson's Disease, akinesia manifests as difficulty starting movements, reduced spontaneous movements like blinking or arm swing while walking, and a mask-like…

Alarm Fatigue(also: Alert Fatigue, Notification Fatigue)

A phenomenon in which an individual becomes desensitised to alarms, alerts, or notifications due to their excessive frequency, repetitive nature, or lack of meaningful context, leading the person to ignore, snooze, or dismiss them. In healthcare and medication management, alarm…

Albinism(also: Oculocutaneous Albinism, Ocular Albinism)

A group of inherited conditions characterized by reduced or absent melanin pigment production, affecting the skin, hair, and eyes. Ocular effects commonly include reduced visual acuity, nystagmus (involuntary eye movements), photophobia (light sensitivity), and reduced depth…

Alexia(also: Acquired Dyslexia, Word Blindness)

An acquired inability to read that results from brain damage, typically from stroke or traumatic brain injury, as distinct from developmental dyslexia which is present from childhood. People with alexia may lose the ability to recognize written words despite retaining other…

Alexithymia

A subclinical condition in which a person has marked difficulty identifying, describing, and distinguishing their own emotions, often accompanied by an externally oriented thinking style and limited imagination about inner states. Alexithymia commonly co-occurs with autism,…

Algebra Earcon(also: Mathematical Earcon, Math Sound)

A non-speech auditory cue designed to represent the structural components of mathematical expressions, allowing blind users to perceive the overall shape and nesting of an expression without relying solely on sequential speech output. Algebra earcons use variations in rhythm,…

Algorithmic Audit(also: AI Audit, Algorithmic Auditing)

A structured evaluation of an algorithmic system that measures how its behaviour differs across users, groups, or contexts - typically to surface bias, fairness failures, or disparate impact. Accessibility-oriented audits go beyond aggregate accuracy to look at where and why a…

Algorithmic Bias(also: AI Bias, Machine Learning Bias)

Systematic and unfair discrimination embedded in the outputs of algorithmic systems, arising from biased training data, flawed model design, or unrepresentative development processes. For people with disabilities, algorithmic bias manifests in multiple ways: voice assistants…

Algorithmic Decision-Making(also: ADM, Automated decision-making)

The use of software systems — from rule-based logic to machine learning models — to make or substantially inform decisions that affect individuals, such as eligibility for benefits, credit, housing, or employment. In public services, algorithmic decision-making is often deployed…

Algorithmic Discrimination(also: AI Discrimination, Automated Discrimination)

The systematic disadvantaging of specific groups through the operation of AI-driven systems, whether intentional or emergent. For people with disabilities, algorithmic discrimination occurs across many domains: employment (AI hiring tools screening out disabled applicants),…

Algorithmic Harm(also: AI Harm, Algorithmic Negative Outcome)

Any difficulty, disadvantage, or injury caused by the use of AI-driven systems, ranging from mere inconvenience to material harm. For people with disabilities, documented algorithmic harms include denial of vital resources (welfare benefits, employment, housing, education),…

Algorithmic Hiring(also: AI Hiring, Hiring AI, AI-Enabled Hiring)

The use of algorithmic systems — including machine learning and large language models — to source, screen, rank, or select job candidates. Proponents argue algorithmic hiring reduces human bias and scales review; critics show it can amplify bias against disabled, Black, female,…

Algorithmic Moderation(also: Automated Moderation, AI Content Moderation)

Algorithmic moderation refers to the use of automated systems, including machine learning models and rule-based filters, to identify, flag, rank, or remove content on digital platforms without direct human review of each decision. It enables platforms to process content at…

Algorithmic accountability(also: AI accountability)

The principle that organizations and individuals responsible for creating and deploying algorithmic systems should be held responsible for the outcomes and impacts of those systems. In accessibility contexts, algorithmic accountability addresses who is responsible when…

Algorithmic bias(also: AI bias, Machine learning bias, Algorithmic discrimination)

Systematic and unfair errors in the outputs of automated decision-making systems that disadvantage particular groups of people. For people with disabilities, algorithmic bias arises from underrepresentation in training datasets, historical discrimination encoded in data, and…

Algospeak(also: Algorithm-Friendly Language, Algo-Speak)

The practice of using code words, creative spellings, or substitutions in online content to avoid algorithmic detection, censorship, or demonetization by social media platforms. Examples include spelling "lesbian" as "le$bian" or "le dollar bean" on TikTok. While algospeak…

Alliance for Technology Access(also: ATA)

The Alliance for Technology Access (ATA) was a U.S. national network of community-based, consumer-driven technology resource centers founded to make assistive technology accessible to people with disabilities. Headquartered in San Rafael, California, the network grew to include…

Allistic(also: Non-Autistic)

A term used to describe people who are not autistic, regardless of whether they are neurotypical in other respects. The term was created within autistic communities to provide a specific counterpart to "autistic" that does not frame autism as deviation from a norm. Using…

Allocative Harm(also: Allocational Harm)

A category of algorithmic harm in which an automated system disproportionately withholds opportunities, resources, or services from certain individuals or groups - often because those groups are underrepresented or atypically represented in training data. In accessibility,…

Allocentric(also: Allocentric Reference Frame, World-Centred Reference Frame)

A spatial reference frame in which locations and directions are defined relative to external landmarks or a fixed coordinate system, independent of the observer's own position or orientation. For example, "the shop is north of the park" or "there are two chairs side by side" are…

Allyship(also: Accessibility Allyship, Disability Allyship)

The practice of non-disabled people (or people without a specific disability) actively supporting disabled colleagues by advocating for accessibility, following accommodation norms, and helping identify and address barriers. In accessibility contexts, allyship includes actions…

Alphabet Board(also: Letter Board, Spelling Board, Communication Board)

A low-technology communication tool displaying letters of the alphabet that enables people who cannot speak to spell out words and messages by pointing to, gazing at, or otherwise indicating individual letters. Alphabet boards are among the simplest and most widely used AAC…

Alt Text(also: Alternative Text, Alt Attribute, Image Description)

A textual description of an image that is embedded in the HTML code and read aloud by screen readers, providing blind and low vision users with information about visual content. Effective alt text is concise, descriptive, and context-appropriate — a decorative image may need…

Alt Text Authoring(also: Alt Text Writing, Image Description Authoring)

The process of composing alternative text descriptions for digital images, undertaken by content authors, developers, or dedicated accessibility specialists. Research has identified several barriers to effective alt text authoring, including authors not knowing what to include,…

Alt text(also: Alternative text, Text alternative)

A textual description of non-text content (primarily images) provided via the HTML alt attribute, read by screen readers and displayed when images cannot be loaded. Required by WCAG Success Criterion 1.1.1 (Level A), alt text should convey the same information or function as the…

Alternative Input Device(also: Alternative Input, Adapted Input, Alternative Access)

Any computer input device used in place of a standard keyboard and mouse by people who cannot operate conventional input hardware due to physical, motor, or other disabilities. Alternative input devices include head controls, eye-gaze systems, sip-and-puff switches, single…

Alternative Input Method(also: Alternative Input, Non-Standard Input)

Any method of providing input to a computer or device that differs from the conventional keyboard, mouse, and touchscreen interfaces. Alternative input methods are essential for people with motor, sensory, or cognitive disabilities who cannot use standard input devices…

Alternative Text(also: Alt Text, Alt Attribute)

Text associated with an image that serves the same purpose and conveys the same essential information as the image. Alternative text is a fundamental web accessibility requirement specified in WCAG, enabling screen reader users to understand image content. Standards for writing…

Alternative input device(also: Alternative access method, Switch access)

Any input method that replaces or supplements standard keyboard, mouse, or joystick interfaces to enable people with motor impairments to operate computers, wheelchairs, and other technology. Examples include sip-and-puff controllers, eye-tracking systems, head switches, voice…

Always-On Computing(also: Always-available computing, Continuous computing)

A model of interaction in which computing devices — particularly wearables such as smartwatches, AR glasses, and fitness trackers — remain continuously active and accessible throughout the day rather than being engaged only for discrete tasks. Always-on computing shifts design…

Alzheimer's Disease(also: Alzheimer's, AD)

A progressive neurodegenerative disease and the most common cause of dementia, accounting for 60-80% of cases. Alzheimer's disease causes gradual decline in memory, thinking, and reasoning skills, eventually affecting the ability to perform everyday activities. The condition…

Amazon Alexa(also: Alexa, Echo)

A cloud-based voice assistant developed by Amazon, available on Echo smart speakers, Echo Show smart displays, and third-party devices. Users interact with Alexa through wake-word-activated voice commands to perform tasks such as setting reminders, playing music, controlling…

Amazon Mechanical Turk(also: AMT, MTurk, Mechanical Turk)

A crowdsourcing marketplace operated by Amazon that enables individuals and businesses to distribute tasks (called Human Intelligence Tasks or HITs) to a distributed workforce who complete them remotely for small payments. AMT has been widely used in HCI and accessibility…

Ambient Audio(also: Ambient Sound, Environmental Audio, Background Audio)

The background sound of an environment — voices, traffic, water, wind, music, birdsong — captured incidentally rather than as the main focus of a recording. In accessible photography and audiophotography tools, ambient audio is often recorded automatically in the seconds leading…

Ambient Display(also: Ambient Interface, Peripheral Display)

A display or interface that communicates information through subtle environmental changes — such as colour shifts, lighting changes, or gentle sounds — that can be perceived at the periphery of a user's attention without demanding direct focus. In accessibility contexts, ambient…

Ambient Intelligence(also: AmI)

An environment enriched with networked, sensor-equipped devices that are sensitive and responsive to the presence and needs of people within it. Ambient intelligence systems anticipate user requirements by learning preferences and behaviours over time, and adapt their responses…

Ambient assisted living(also: AAL, Smart home assistive living)

Technology systems embedded in the home environment — including sensors, microphones, and smart devices — that monitor and support older adults or people with disabilities to live independently and safely. AAL aims to detect emergencies like falls, remind about medications, and…

Ambiguous Loss

Ambiguous loss, a concept articulated by Pauline Boss, is 'a situation of unclear loss that remains unverified and thus without resolution'. Boss distinguishes two types: physical loss where someone is 'gone, but not for sure' (for example, a missing person) and psychological…

Ambiguous keyboard(also: T9 input, Multi-tap disambiguation)

A text entry method in which multiple letters are mapped to each physical key, requiring disambiguation algorithms (typically dictionary-based) to determine the intended word from the sequence of key presses. Originally popularized by T9 predictive text on mobile phone numeric…

Ambisonics(also: Ambisonic audio, Ambisonic sound)

A full-sphere surround sound technique that captures and reproduces audio from all directions — including above and below the listener — using a spherical harmonic representation of the sound field. Originally developed by Michael Gerzon in the 1970s, ambisonics differs from…

Amblyopia(also: Lazy eye)

A neurodevelopmental vision disorder in which one eye has reduced visual acuity that cannot be fully corrected with glasses or contact lenses, caused by abnormal visual development in early childhood. The brain favors one eye and partially suppresses input from the weaker eye,…

American Sign Language(also: ASL)

A complete, natural language with its own grammar, syntax, and vocabulary, expressed through hand shapes, facial expressions, and body movements, used primarily by Deaf communities in the United States and parts of Canada. ASL is not a signed version of English—it has distinct…

American Sign Language(also: ASL, Ameslan)

A complete, natural language that uses hand movements, facial expressions, and body posture to convey meaning, serving as the primary language of many Deaf people in the United States and parts of Canada. ASL has its own grammar and syntax distinct from English and is not a…

Americans with Disabilities Act(also: ADA, ADA 1990)

The Americans with Disabilities Act (ADA) is landmark US civil rights legislation enacted in 1990 that prohibits discrimination against individuals with disabilities in all areas of public life, including employment, education, transportation, and public accommodations. Title II…

Amnesia(also: Memory Loss, Amnestic Disorder)

A neurological condition characterised by the partial or complete inability to recall past experiences (retrograde amnesia) or to form new memories (anterograde amnesia). Amnesia results from damage to brain structures responsible for memory processing, commonly caused by…