Glossary

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Flat Affect(also: Blunted Affect, Reduced Expressiveness)

Flat affect refers to a significant reduction in the outward expression of emotions, where a person shows little or no visible emotional response through facial expressions, voice tone, or body language. In the context of accessibility and neurodiversity, flat affect is commonly…

Flatbed Scanner(also: Desktop Scanner, Document Scanner)

A device that uses a flat glass surface on which documents or books are placed face-down to be digitised by a sensor that moves beneath the glass. In assistive technology, flatbed scanners have been used with optical character recognition (OCR) and text-to-speech software to…

Fleiss's Kappa(also: Fleiss Kappa)

A statistical measure of inter-rater reliability for categorical ratings assigned by three or more raters, extending Cohen's Kappa beyond the two-rater case. In accessibility research, Fleiss's Kappa is commonly used to validate qualitative coding of user reviews, heuristic…

Flesch Reading Ease(also: Flesch Readability Score, Flesch Score, FRE)

A readability formula developed by Rudolf Flesch in 1948 that rates text on a 100-point scale based on average sentence length and average number of syllables per word. Higher scores indicate easier-to-read text: scores of 60-70 are considered suitable for a general audience,…

Flesch-Kincaid Grade Level(also: Flesch-Kincaid, FKGL, Flesch-Kincaid readability)

A readability formula that estimates the U.S. school grade level required to comfortably read a given English text, based on average sentence length and average syllables per word. Developed for the U.S. Navy in 1975 by Rudolf Flesch and J. Peter Kincaid, the formula is widely…

Flexible Learning(also: Flexible Instruction, Flexible Pedagogy)

An educational approach that provides students with choices in how, when, where, and at what pace they learn. Flexible learning may include options such as recorded lectures that can be watched at variable speeds, asynchronous participation, multiple formats for content…

Flexible Media(also: Object-Based Media)

A method of producing audiovisual media in which different components of the content (such as audio tracks, video angles, and subtitle layers) are stored as separate elements and assembled at runtime based on viewer preferences and needs. Flexible media enables individual…

Flexible Work(also: Flexible Work Arrangements, Flexible Employment)

Work arrangements that allow variation in schedule, location, pace, or structure, including remote work, flexible hours, part-time options, and self-directed work. For many disabled people, flexible work is not a perk but a fundamental accessibility requirement, as rigid…

Floating Action Button(also: FAB)

A circular button that floats above the user interface in Android apps, typically representing the primary action on a screen. Defined by Google's Material Design guidelines, FABs usually display a simple icon (such as a plus sign, pencil, or heart) without visible text labels.…

Floor Holding(also: Holding the Floor, Turn Holding)

The conversational practice of maintaining one's turn to speak, signaling to others that one has not finished and intends to continue. For AAC users, floor holding is particularly challenging because the time required to compose messages creates long pauses that communication…

Floor Plan(also: Floor Map, Building Plan, Building Layout)

A floor plan is a scaled diagram of a room or building viewed from above, showing the arrangement of rooms, corridors, exits, and other spatial features. In accessibility contexts, floor plans present significant challenges for people with visual impairments because they are…

Flourishing(also: Developmental Flourishing, Human Flourishing)

An orientation in design and HCI that measures success not by task completion or outcome equivalence but by the extent to which a system supports individuals' subjective well-being, personal significance, agency, and ongoing development. The concept draws on positive psychology,…

Flow(also: Flow state, Optimal experience, Being in the zone)

A psychological state of complete absorption in an activity, characterized by focused concentration, loss of self-consciousness, altered sense of time, and intrinsic enjoyment. Coined by psychologist Mihaly Csikszentmihalyi, flow occurs when a person's skills are well-matched to…

Flow State(also: Flow, Optimal Experience, Being in the Zone)

A mental state of complete immersion and focused engagement in an activity, characterized by a balance between challenge level and skill level. In accessible design, achieving flow state is important for learning systems and games because it maximizes engagement without causing…

Flow Theory(also: Flow State, Flow)

A psychological theory proposed by Mihaly Csikszentmihalyi describing the state of deep immersion and intrinsic enjoyment that occurs when a person is fully engaged in an activity whose challenge level closely matches their skill level. Flow is characterized by clear goals,…

Flowchart

A type of node-link diagram used to represent a process, workflow, or algorithm as a sequence of steps connected by directional arrows. Flowcharts use conventional shape vocabularies (rectangles for process steps, diamonds for decisions, ovals for start/end) so that structure is…

Fluctuating Access Needs(also: Dynamic Access Needs, Variable Access Needs)

Accessibility requirements that change over time for a single individual, varying based on factors such as energy levels, symptoms, time of day, environment, medication, menstrual cycle, cognitive load, and fatigue. Common among people with chronic illnesses, neurodivergence,…

Fluctuating Disability(also: Variable Disability)

A disability whose symptoms and severity vary over time, sometimes day to day or even hour to hour. People with fluctuating disabilities may experience periods of relatively high function alternating with periods of significant impairment. This variability creates challenges for…

Fluency(also: Text fluency, Grammatical fluency)

In natural language processing and text simplification, fluency is the degree to which a piece of text is grammatically correct and reads naturally in the target language. It is one of three standard evaluation dimensions for automatic text simplification alongside complexity…

Fluid Traversal(also: Fluid Navigation)

A navigation design principle for screen reader interfaces that aims to mirror the flexibility of sighted visual attention. Fluid traversal has two key properties: it should be concise (requiring minimal key presses or actions to move between parts of a representation) and…

Fluid intelligence(also: Fluid reasoning, Gf)

The cognitive ability to reason, solve novel problems, and identify patterns without relying on previously acquired knowledge or skills. Fluid intelligence typically declines with age and is commonly measured through tasks involving pattern recognition, inductive reasoning, and…

Focus Group(also: Focus Group Discussion, Group Interview)

A qualitative research method in which a small group of participants (typically 3-10) with shared characteristics discuss a topic guided by a moderator, allowing researchers to explore perspectives, opinions, and experiences through group interaction. Focus groups are considered…

Focus Indicator(also: Focus Ring, Visible Focus, Focus Outline)

A visual cue that shows which interactive element on a page or in an application currently has keyboard focus. Focus indicators are typically rendered as an outline, border, or highlight around the focused element. They are essential for keyboard users and screen magnification…

Focus Management(also: Focus Control, Programmatic Focus)

The practice of controlling which element on a web page or application receives keyboard focus, and ensuring that focus moves in a logical and predictable manner as users interact with the interface. Focus management is one of the most challenging aspects of web accessibility…

Focus Mode

A privacy technique in visual assistance technologies that spotlights a specific object of interest while obfuscating or hiding all other elements in the image or video. For example, a user might activate focus mode to view only a microwaveable meal while everything else in the…

Focus Order(also: Tab Order, Focus Sequence)

The sequence in which interactive elements receive keyboard focus when a user presses the Tab key or uses other keyboard navigation. In accessibility, a logical focus order that follows the visual and semantic structure of the page is essential for screen reader users and…

Focus and Context(also: Focus+Context, Detail in Context)

An information visualization and interaction design principle that simultaneously presents detailed information about a specific item of interest (focus) alongside an overview of the surrounding structure or environment (context). In accessibility, the focus+context approach is…

Focus trap(also: Keyboard trap, Focus lock)

A web accessibility barrier in which keyboard focus becomes confined to a particular element or region of a page, preventing the user from navigating away using standard keyboard commands. Focus traps are especially problematic for screen reader users and keyboard-only users,…

Focus+Context(also: Focus plus Context, Focus and Context)

A visualization interaction paradigm that integrates a detailed focus region and its surrounding context into a single unified view, rather than separating them. Techniques include fisheye views, semantic zooming, and lenses that distort or overlay content so users can see fine…

Focusable Element(also: Keyboard Focusable, Focus Target)

A GUI element that can receive input focus, allowing users to interact with it via keyboard, switch device, or assistive technology. For screen reader users navigating mobile apps, an element without focus enabled is essentially invisible—they cannot select, activate, or even…

Focusmate

An online platform that facilitates virtual body doubling by matching users with accountability partners for timed video co-working sessions. Users keep their cameras on, state their goals at the beginning of each session, and report on progress at the end. Focusmate creates…

Font Accessibility(also: Accessible Fonts, Dyslexia-Friendly Fonts)

The selection and design of typefaces to maximize readability for people with disabilities, particularly dyslexia and low vision. Research has evaluated various font properties for accessibility, finding that sans serif fonts, monospaced fonts, and fonts with distinct letter…

Font Embedding(also: Embedded Fonts, PDF Font Embedding)

The practice of including the complete font data within a PDF document so that the text can be accurately rendered and read regardless of whether the font is installed on the viewer's system. Font embedding is an accessibility requirement because non-embedded fonts can cause…

Font Size(also: Text Size, Type Size, Point Size)

The measurement of how large characters in a typeface are displayed, typically expressed in points (pt), pixels (px), or relative units (em, rem). Font size is a critical accessibility concern because text that is too small creates barriers for people with low vision, older…

Food Desert(also: Food Swamp, Low Food Access Area)

A geographic area, typically in low-income communities, where residents have limited access to affordable and nutritious food due to the absence of nearby grocery stores or fresh food retailers. Food deserts disproportionately affect people with disabilities, who may face…

Foot-Based Interaction(also: Foot Input, Foot Gesture Interaction)

An interaction technique that uses foot movements and gestures as input for controlling digital devices. Foot-based interaction is particularly relevant for people with upper body motor impairments who have functional lower limbs but cannot use their hands, including people with…

Force Feedback(also: Haptic Force Feedback, Kinesthetic Feedback)

A type of haptic technology that applies physical forces to the user through a device such as a stylus, joystick, or glove, simulating the sensation of touching or interacting with virtual objects. Unlike vibrotactile feedback which only provides vibrations, force feedback can…

Force Feedback Joystick(also: Haptic Joystick, Rumble Joystick)

An input device that combines a traditional joystick with motors or actuators that apply physical resistance, vibration, or directional forces to the user's hand, providing tactile information about the virtual environment being navigated. In accessibility applications, force…

Force Field(also: Haptic Force Field, Virtual Force Field)

In haptic interface design, a computational model that defines attractive or repulsive forces at each point in a two-dimensional workspace, used to represent graphical user interface elements as tactile objects. When a user moves a haptic pointing device through a force field,…

Force-Sensing Resistor(also: FSR, Force Sensor)

A sensor that decreases in electrical resistance when physical pressure is applied to its surface. Force-sensing resistors are commonly used in assistive technology and accessibility applications to create pressure-sensitive input devices, haptic feedback systems, and adaptive…

Force-sensitive resistor(also: FSR, Pressure sensor)

An electronic sensor whose electrical resistance changes in response to applied physical pressure, enabling detection of both the presence and intensity of touch or force. In accessibility applications, force-sensitive resistors offer advantages over capacitive touchscreens…

Forced Alignment(also: Phonetic Alignment, Phone-Level Alignment)

Forced alignment is an automatic speech processing technique that aligns a speech recording with its known transcription at the phoneme or word level. Unlike free speech recognition which determines the most likely sequence of sounds, forced alignment constrains the recognizer…

Forced Intimacy

Forced Intimacy is a concept coined by disability and transformative justice activist Mia Mingus that describes the experience of disabled people being expected to share very personal information with non-disabled people simply to access basic services, navigate public spaces,…

Foreground Sound(also: FS)

In sonification-based web accessibility interfaces, a non-speech audio cue that represents individual content elements within a web page, such as links, images, or text blocks. Foreground sounds are designed to be short, distinct, and attention-grabbing, contrasting with the…

Forgotten Margins

A term describing disabled communities and populations that remain overlooked by mainstream accessibility research and practice, typically those at the intersection of disability and other forms of marginalization such as poverty, criminalization, racial discrimination, or…

Forking(also: Content Forking, Branching)

A collaborative mechanism borrowed from software version control where a user creates a copy of an existing work to modify independently while preserving the original. In audio description authoring, forking allows describers to duplicate an existing set of descriptions—whether…

Form Accessibility(also: Accessible Forms, Form A11y)

The practice of designing and implementing digital forms so they can be effectively completed by people using assistive technologies, particularly screen readers. Key requirements include: every form field must have a programmatically associated label that clearly describes the…

Form Factor(also: Device Form Factor, Handset Form Factor)

Form factor refers to the overall physical size, shape, weight, and mechanical configuration of a device — for mobile phones this includes distinctions like candy-bar, clamshell (flip), slide-out keyboard, foldable, and modern all-touch slab. Form factor has direct accessibility…

Form Label(also: Input Label, Form Field Label)

A text label programmatically associated with an interactive form control (such as a text input, button, checkbox, or dropdown) that identifies the purpose or function of that control to all users. In HTML, form labels are typically implemented using the <label> element linked…

Form Labeling(also: Form Labels, Input Labels, Programmatic Labels)

The practice of providing descriptive text labels that are programmatically associated with their corresponding form input fields, enabling screen readers to announce what information is expected in each field. Proper form labeling uses HTML label elements with a "for" attribute…