Glossary

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Lexical Semantics

The branch of linguistics concerned with the meaning of words and the relationships between word meanings, including synonymy, antonymy, and the semantic roles words can fill in sentences. In assistive technology, lexical semantic knowledge is used in AAC systems and text…

Lexical Signing(also: Lexical Sign, LS)

In American Sign Language and related signed languages, the production of meaning by syntactically combining individual lexical signs drawn from the language's vocabulary — analogous to combining words into sentences in a spoken or written language. Lexical signing is contrasted…

Lexical Simplification(also: Word-Level Simplification)

A form of text simplification that focuses on replacing complex, uncommon, or technical words with simpler, more familiar alternatives. Lexical simplification is particularly relevant for readers with limited vocabulary, including people who are deaf or hard of hearing (for whom…

Lexile Framework(also: Lexile, Lexile Measure)

A commercial readability framework developed by MetaMetrics that places both texts and readers on a common scale — the Lexile measure — to support matching readers with materials at an appropriate level of challenge. A text's Lexile measure is computed from sentence length and…

Lexile Score(also: Lexile Measure, Lexile Level)

A standardised measure of text complexity and reading ability, expressed on the Lexile scale (roughly 0L to 1600L+). A Lexile text measure reflects sentence length and word frequency; a Lexile reader measure reflects the reader's ability. For accessibility, Lexile scores provide…

LiDAR(also: Light detection and ranging, Laser scanning)

A remote sensing technology that measures distances by emitting laser pulses and analysing the reflected light, producing precise three-dimensional point clouds of the surrounding environment. In accessibility, LiDAR has multiple applications: it is used to assess pedestrian…

Liberatory access(also: Liberation-oriented access)

An approach to accessibility that goes beyond inclusion and assimilation to challenge the broader conditions of ableism and exclusion that create inaccessibility in the first place. Coined by disability justice activist Mia Mingus, liberatory access strives not just to help…

Libras(also: Brazilian Sign Language, Língua Brasileira de Sinais)

The official sign language of the Deaf community in Brazil, recognized by Brazilian federal law (Law No. 10.436/2002) as a legitimate means of communication and expression. Libras has its own grammar, syntax, and linguistic structure distinct from spoken Brazilian Portuguese. It…

Librosa

An open-source Python library for audio and music signal analysis, widely used in music-information retrieval and accessibility research to extract low-level acoustic features such as tempo, RMS energy, spectral centroid, zero-crossing rate, chroma, and mel-frequency cepstral…

Life Story Work(also: Life Story, Biography Work, Digital Biography)

A person-centered approach to care that involves gathering and sharing information about an individual's life history, preferences, relationships, and experiences. In dementia care, life story work helps caregivers see the person behind the condition and supports meaningful…

Lifelogging(also: Life Logging, Digital Lifelogging)

Lifelogging is the practice of automatically and continuously capturing data about a person's daily life using sensors, cameras, GPS, and other digital tools, typically worn or carried by the individual. In the context of accessibility, lifelogging data can be used to build…

Lifestyle Modelling(also: Lifestyle Monitoring, Lifestyle Modeling)

Lifestyle modelling is the correlation of a person's observed day-to-day activities — sleeping, eating, moving between rooms, interacting with objects — with inferences about their well-being, usually using data from ambient sensors in the home. In accessibility and…

Light Sensitivity(also: Photophobia, Photosensitivity)

An abnormal sensitivity to light that causes discomfort, pain, or visual disruption. Many people with low vision experience light sensitivity, which can be exacerbated by bright overhead lighting, backlit screens, glare from reflective surfaces, and high-contrast environments.…

Lighthouse(also: Google Lighthouse, Chrome Lighthouse)

An open-source automated tool developed by Google for auditing web page quality, including performance, accessibility, SEO, and progressive web app compliance. Lighthouse runs in Chrome DevTools, as a browser extension, or via command line, and produces scores from 0-100 for…

Likert Scale(also: Likert-Type Scale)

A psychometric rating scale commonly used in surveys and usability studies where respondents indicate their level of agreement or satisfaction on a symmetric scale, typically with 5 or 7 points ranging from "strongly disagree" to "strongly agree." Likert scales are standard…

Likert Scale(also: Likert-type Scale, Rating Scale)

A psychometric scale commonly used in surveys and questionnaires where respondents indicate their level of agreement with a statement, typically using options ranging from "strongly disagree" to "strongly agree." In accessibility research, Likert scales are frequently used to…

Limb Difference(also: Limb Deficiency, Upper-Limb Difference)

Limb difference is a term used to describe the absence or malformation of one or more limbs or parts of limbs. It can be congenital (present from birth) or acquired through amputation due to injury, disease, or surgery. The term "limb difference" is increasingly preferred over…

Lime Lighter

A specialized hardware and software system developed by Dancing Dots, a company led by a blind musician, for reading and navigating music scores accessibly. The Lime Lighter includes features like Bluetooth pedal control for hands-free page turning, Optical Music Recognition,…

Liminality(also: Liminal State, Liminal Period)

A transitional state of being "betwixt and between" established social positions, originally described by anthropologist Victor Turner. In accessibility contexts, liminality refers to the uncertain, in-between period people experience when acquiring a disability, adopting…

Limited Mobility(also: Reduced Mobility, Mobility Impairment)

A condition where a person has restricted ability to move their body or specific limbs, which may affect walking, reaching, grasping, or fine motor control. Limited mobility encompasses a wide range of conditions including paraplegia, quadriplegia, muscular disorders, joint…

Line Chart Accessibility(also: Accessible Line Graphs, Chart Accessibility)

The practice of making line charts and graphs perceivable and understandable by people with visual impairments through alternative representations such as tactile graphics, sonification, speech descriptions, or multimodal interfaces. Accessible line charts must convey not just…

Line Graph(also: Line Chart, Line Plot)

A type of data visualization that displays information as a series of data points connected by straight line segments, commonly used to show trends over time or relationships between variables. Line graphs are a fundamental tool in mathematics education and data analysis, but…

Line Spacing(also: Leading, Line Height, Line-Height)

The vertical distance between lines of text, controlled in CSS by the line-height property. Adequate line spacing is important for readability and accessibility, particularly for people with low vision, dyslexia, or cognitive disabilities. Research shows that both younger and…

Line Standing(also: Queueing, Standing in line, Line navigation)

The everyday social activity of waiting in an ordered queue — at a cashier, bus stop, check-in counter, or reception desk. For blind people, line standing is an often-overlooked accessibility challenge: the end of the line is a dynamically moving position that cannot be located…

Line Tracing

A reading technique in which a user physically follows lines of text with their finger or a pointing device, typically while receiving feedback to maintain accurate positioning. In assistive technology contexts, line tracing is fundamental to finger-based reading systems for…

Linear Communication Model(also: Shannon-Weaver Model, Sender-Receiver Model)

A model of communication in which information flows in one direction from a sender to a receiver through a channel, with no feedback mechanism. In the context of AAC, a linear model means the user constructs and delivers a message through the device while the communication…

Linear Discriminant Analysis(also: Fisher Discriminant Analysis, Fisherfaces)

A statistical method used in pattern recognition and machine learning that finds a linear combination of features to best separate two or more classes of objects. In the context of face recognition, LDA (also known as the Fisherfaces method) projects face images into a…

Linear Interaction(also: Sequential Interaction, Single-path Navigation)

An interface design pattern in which users engage with only one screen or task at a time, following a single sequential path rather than managing multiple overlapping windows, tabs, or concurrent contexts. Linear interaction reduces cognitive load by eliminating the need to…

Linear Notation(also: Linear Mathematical Notation)

A system for representing mathematical expressions in a single line of text, as opposed to the conventional two-dimensional spatial layout used in print mathematics. In standard mathematical notation, spatial arrangement carries meaning — fractions stack numerators above…

Linear Scanning(also: Row-column scanning, Automatic scanning)

An input method for AAC devices and on-screen keyboards where selections are highlighted sequentially, typically row by row and then item by item, allowing users with severe motor impairments to select options using a single switch. The system automatically moves through options…

Linearization(also: Content linearization, Serial presentation)

The process by which screen readers convert two-dimensional visual page layouts into a single sequential audio stream, reading content in DOM order. Linearization strips away spatial relationships, visual groupings, and layout cues that sighted users rely on for navigation and…

Lingraphica

A commercially available computerized visual communication system designed to help people with aphasia communicate through icon-based sentence construction. Lingraphica provides a vocabulary of purpose-designed icons that users can arrange to form phrases and sentences, with the…

Linguicism(also: Linguistic Discrimination, Language Discrimination)

Discrimination or prejudice against individuals or groups based on the language or dialect they use, often intertwined with racism and ableism. In the Deaf community, linguicism commonly shows up as the privileging of spoken-language and English-based systems (Signed Exact…

Linguistic Accessibility

The principle that information, services, and opportunities for participation should be available in a person's preferred language and communication modality. For Deaf and Hard of Hearing individuals, linguistic accessibility means providing content and interaction opportunities…

Linguistic Imperialism(also: Language Imperialism)

The imposition of one language or language modality over others, often by dominant groups over minority language communities. In deaf contexts, linguistic imperialism manifests when spoken language is privileged over sign language, such as forcing deaf individuals to use…

Linguistic Minority(also: Language Minority)

A group whose primary language differs from the dominant language of the surrounding society, often placing them at a disadvantage in education, employment, civic participation, and access to information. Deaf sign language users are frequently described as a linguistic and…

Link Annotation(also: Link Augmentation, Link Labelling)

The practice of adding supplementary information to hyperlinks to help users make informed navigation decisions before clicking. In web accessibility, link annotations may include the accessibility level of the target page, the file type and size of linked documents, or…

Link Context(also: Anchor Context, Link Surrounding Context)

The text and information surrounding a hypertext link that helps users understand the link's purpose and destination. For sighted users, link context is often apparent from the visual layout — headings, images, and nearby text provide clues about what a link does. For screen…

Link Preview(also: Link Destination Preview, Link Target Preview)

Information about the content or nature of a hypertext link's destination page, provided to users before they follow the link. Link previews help users make informed navigation decisions, reducing the costly trial-and-error of following links to discover their content and then…

Link Purpose(also: Link Purpose (In Context), WCAG 2.4.4, Link Text)

A WCAG 2.4.4 Level A success criterion requiring that the purpose of each link be determinable from the link text alone, or from the link text together with its programmatically determined context (surrounding sentence, list item, table cell, containing paragraph). Links worded…

Linked Data(also: Linked Open Data, LOD)

A method of publishing structured data on the web so that it can be interlinked and queried across different sources using standard web technologies such as URIs and RDF (Resource Description Framework). In accessibility contexts, linked data has been proposed as a way to…

Linked Data(also: Linked Open Data, LOD)

A method of publishing structured data on the web so that it can be interlinked and queried across different sources using Semantic Web technologies such as RDF, URIs, and SPARQL. Linked Data principles enable disparate datasets — for example, transport accessibility information…

Lip Reading(also: Speechreading, Visual Speech Perception)

The practice of interpreting speech by visually observing the speaker mouth movements, facial expressions, and gestures. While commonly associated with deaf and hard of hearing individuals, lip reading is also used by people with ADHD and auditory processing difficulties as a…

Lip-reading(also: Speechreading, Speech Reading, Visual Speech Perception)

The practice of understanding speech by visually interpreting the movements of the lips, face, and tongue, often used by deaf and hard-of-hearing individuals as a communication strategy. Lip-reading relies on watching the mouth region and facial expressions to decode spoken…

Lipreading(also: Lip reading, Speechreading (narrow sense))

The practice of understanding spoken language by visually interpreting the movements of a speaker's lips, tongue, teeth, jaw, and facial expression. Lipreading is used by many Deaf and Hard-of-Hearing people — especially those who acquired hearing loss after learning spoken…

List-Based Interface(also: List View, Linear Interface)

An interface layout that presents information as a sequential list rather than in a grid, table, or spatial layout. In accessibility contexts, list-based interfaces are generally more screen reader-friendly than grid layouts because they follow a natural linear reading order,…

Listenability(also: Auditory Readability, Speech-Output Quality)

A web-accessibility usability metric that measures how appropriate a page's rendered text is when read aloud by a screen reader or voice browser — complementary to, and distinct from, raw WCAG conformance. Listenability penalises meaningless or placeholder ALT text (such as…

Listener Feedback(also: Listener Response, Feedback Signals)

The signals produced by a listener during conversation that communicate their attentiveness, understanding, agreement, confusion, or emotional response to the speaker without taking a full conversational turn. Listener feedback encompasses verbal backchanneling ("mm-hmm,"…

Listening Fatigue(also: Auditory Fatigue)

The mental and physical exhaustion experienced from sustained effortful listening, commonly reported by people who are Hard of Hearing or use hearing aids and cochlear implants. Listening fatigue can reduce comprehension, concentration, and engagement over time. In the context…

Listening Rate(also: Comprehension Speed, Listening Speed)

The maximum speed at which an individual can accurately comprehend spoken or synthesized speech, typically measured as a normalized value or in words per minute. Research shows that experienced screen reader users can achieve listening rates far exceeding typical human speech…