Glossary

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Non-manual markers(also: NMM, Non-manual signals, Facial grammar)

Linguistic features in sign languages that are conveyed through facial expressions, head tilts, eye gaze direction, mouth movements, and body posture rather than through hand signs. Non-manual markers serve grammatical functions in ASL and other sign languages — including…

Onomatopoeia

Words that phonetically imitate or suggest the sound they describe, such as "buzz," "crash," "swoosh," or "sizzle." In captioning, onomatopoeia is one approach to representing non-speech sounds, offering viewers a sense of the acoustic quality of a sound. However, research shows…

Orthographic Depth(also: Orthographic Transparency, Spelling Transparency)

A measure of how consistently a written language maps between its spelling (graphemes) and pronunciation (phonemes). Shallow or transparent orthographies like Spanish, Finnish, and Italian have highly consistent letter-to-sound correspondences, while deep or opaque orthographies…

Orthographic Depth(also: Orthographic Transparency, Spelling Transparency)

The degree of consistency in the relationship between letters (graphemes) and sounds (phonemes) in a writing system. Languages with shallow or transparent orthography — like Finnish, Spanish, and Italian — have highly consistent letter-to-sound mappings, meaning words are…

Paralinguistic Cues(also: Paralanguage, Paralinguistic Features, Non-verbal Vocal Cues)

Aspects of spoken communication that carry meaning beyond the literal words themselves: tone of voice, pitch contour, loudness, rhythm, tempo, stress, pauses, and voice quality. Paralinguistic cues convey emotion, emphasis, sarcasm, uncertainty, speaker identity, and social…

Part of Speech(also: POS, Word Class, POS Tag)

A grammatical category assigned to each word (or, in signed languages, each sign) in a sentence — such as noun, verb, adjective, adverb, pronoun, preposition, or conjunction. Automatic part-of-speech tagging is a foundational step in natural language processing pipelines. In…

Part-of-Speech(also: POS, Word Class, Lexical Category)

The grammatical category of a word — noun, verb, adjective, adverb, preposition, pronoun, conjunction, determiner, and so on. Part-of-speech labels are the basic output of part-of-speech tagging and a foundational input to many accessibility NLP pipelines: readability…

Phonology(also: Sign Language Phonology)

The study of the smallest meaningful units that make up language and the rules governing their combination. In sign languages, phonology describes the building blocks of signs: handshape, location on the body, movement, palm orientation, and non-manual signals. William Stokes…

Pronominal Reference(also: Pronoun Reference, Anaphoric Reference)

The use of pronouns or pronoun-like expressions to refer back to entities previously introduced in a discourse. In spoken and written languages this is typically achieved with words such as "he," "she," "it," or "they"; in American Sign Language and other signed languages,…

Prosodic Breaks(also: Prosodic Pauses, Prosodic Boundaries)

Pauses or breaks in the flow of communication that convey grammatical, syntactic, or emphatic meaning. In sign language, prosodic breaks occur between signs and serve functions similar to intonation and pausing in spoken language — marking sentence boundaries, separating clauses…

Prosody(also: Speech Prosody, Intonation Patterns)

The patterns of stress, rhythm, intonation, and timing in speech that convey meaning beyond the literal words. Prosody communicates emotions, emphasis, questions versus statements, sarcasm, and conversational cues like turn-taking signals. For AAC users relying on text-to-speech…

Psycholinguistics

The scientific study of the cognitive and neural processes that underlie the production, comprehension, and acquisition of language. Psycholinguistic research measures phenomena such as reading and signing rate, comprehension under time pressure, lexical access, and the role of…

Regional Sign Variation(also: Sign Language Dialect, Regional Sign Dialect)

Regional sign variation refers to systematic differences in the form of signs across geographic regions within a single sign language, analogous to dialects in spoken languages. Variation arises from local Deaf school traditions, contact between communities, and historical…

Rhetorical Question (ASL)(also: ASL Rhetorical Question, RHQ)

In American Sign Language, a grammatical construction in which the signer poses a question and then immediately answers it, used as a cohesive rhetorical device rather than as a genuine inquiry. ASL rhetorical questions are marked by specific non-manual signals — typically…

Second Language Acquisition(also: SLA, L2 Acquisition)

The process by which a person learns a language other than their first (native) language. In deaf education and accessibility, second language acquisition theory is particularly relevant because written English is effectively a second language for native signers of American Sign…

Semantic Network(also: Semantic Web, Associative Network)

A knowledge representation structure in which concepts are represented as nodes and the relationships between them as links or edges. In accessibility and AAC contexts, semantic networks model how words and concepts are associated in the human mind, enabling vocabulary tools to…

Semantic distance(also: Semantic similarity, Word embedding distance)

A computational measure of how different two words are in meaning, typically derived from word embedding models like word2vec that represent words as vectors in a high-dimensional space. In caption evaluation for DHH users, semantic distance between an ASR error and the intended…

Sign Duration(also: Sign Speed, Signing Speed)

The average time spent performing individual signs during sign language production, typically measured in seconds. Sign duration is a key parameter in sign language animation that affects both understandability and user satisfaction. Research has shown that DHH users of ASL…

Sign Language Classifier(also: Classifier Sign, Depicting Sign, Classifier Predicate)

A type of sign in sign languages that is not part of a fixed vocabulary but is created dynamically during discourse to represent a class of objects sharing a common shape, size, or physical characteristic. Classifiers function as "super-pronouns" — they replace and describe…

Sign Language Phonology

The study of the smallest meaningful units that make up signs in signed languages, analogous to phonemes in spoken languages. In American Sign Language, signs are composed of phonological parameters including handshape, movement, location (place of articulation), and non-manual…

Sign Linguistics(also: Sign Language Linguistics)

The scientific study of the structure and properties of sign languages. Sign linguistics examines the phonological, morphological, syntactic, and semantic components of visual-gestural languages. Key parameters studied include handshape (approximately 90 distinct configurations…

Sign Phoneme(also: cheremes, sign language phoneme)

The smallest contrastive units in sign language that bear meaning and distinguish one sign from another, analogous to phonemes in spoken language. Sign phonemes include hand shapes, movements, locations, and orientations that combine to form signs. In sign language recognition…

SignWriting

A writing system for sign languages that uses visual symbols to represent handshapes, movements, facial expressions, and body positions. Created by Valerie Sutton in 1974, SignWriting allows sign languages to be written and read without translation into a spoken language. Unlike…

Signing Space(also: Sign Space)

The three-dimensional area in front of a signer where sign language is produced, typically extending from waist to head height and shoulder width to either side. In American Sign Language and other sign languages, this space serves grammatical functions—locations within it can…

Spatial Grammar(also: Spatial Syntax)

Spatial grammar is the set of grammatical rules that signed languages express through the three-dimensional signing space in front of the signer, rather than through linear word order. Signers establish referents at specific spatial loci, use directional verbs that agree with…

Spatial Inflection(also: Verb Agreement, Directional Verb, Inflecting Verb)

A grammatical process in sign languages where the motion path and orientation of a verb sign are modified based on the 3D locations in space that have been assigned to its subject and/or object during discourse. In American Sign Language and many other sign languages, signers…

Spatial Reference (ASL)(also: Spatial Reference Point, Locus, ASL Spatial Reference)

In American Sign Language and other signed languages, the use of points in the signing space in front of the signer as invisible placeholders for entities under discussion — people, objects, or concepts. A signer may point to, sign near, or direct eye gaze toward a particular…

Speech Acts Theory(also: Speech Act Theory, Illocutionary Acts)

A theory from the philosophy of language, originally developed by J.L. Austin and John Searle, which holds that utterances are not just statements of fact but also actions that accomplish things — such as requesting, promising, warning, or commanding. In assistive technology and…

Stokoe Notation(also: Stokoe System)

A notational system for representing the formational components of sign language signs, devised by William C. Stokoe for the 1965 Dictionary of American Sign Language on Linguistic Principles. The system analyzes each sign into three parameters: location (where the sign is…

Syntactic NMS(also: Syntactic Non-Manual Sign)

Non-manual signs that define sentence types and grammatical structure in sign languages. In ASL, syntactic NMS include raised eyebrows for Yes/No questions, furrowed brows and forward head tilt for WH-questions, head shake for negation, and specific facial configurations for…

Syntactic Parse Tree(also: Parse Tree, Syntactic Tree)

A tree-shaped data structure that represents the grammatical structure of a sentence according to a formal grammar. Internal nodes correspond to phrases (noun phrase, verb phrase, clause, sentence) and leaves correspond to individual words or signs. Parse trees are produced…

Transfer Machine Translation(also: Transfer MT, Rule-Based Transfer Translation)

A rule-based machine-translation paradigm that analyses the source text into a syntactic or semantic structure, applies a set of transfer rules to produce a corresponding structure in the target language, and then generates the target surface form. Transfer MT sits between…

Transliteration(also: Sign Language Transliteration)

The word-by-word conversion of text from one system into another — for example, rendering a name in one script using the characters of another. In sign-language accessibility the term has a specific meaning: producing a signed form of spoken or written English by substituting a…

Verb Inflection(also: Sign Language Verb Inflection, Directional Verbs)

In sign languages, verb inflection refers to the modification of a verb sign's movement path, speed, or direction to encode grammatical information such as subject, object, number, and aspect. Unlike spoken languages where inflection typically involves changes to word endings,…

Visual Language(also: Visuo-Gestural Language)

A language that uses the visual-gestural modality for communication, as opposed to the auditory-vocal modality of spoken languages. Sign languages are visual languages that encode information through hand shapes, movements, spatial relationships, facial expressions, and body…

Word importance(also: Lexical importance, Information content)

A measure of how critical a specific word is to the overall meaning of a sentence, typically computed using neural language models that estimate how predictable a word is from its context. In captioning evaluation, word importance helps determine the impact of ASR errors:…

WordNet

A large-scale electronic lexical database of the English language developed at Princeton University, in which nouns, verbs, adjectives, and adverbs are grouped into sets of cognitive synonyms (synsets) linked by semantic and lexical relations. WordNet is designed to model how…