Speech-language pathology glossary: 58 terms explained in plain language

Speech-language pathology has its own vocabulary, and reports, school meetings and research papers use it freely. This glossary defines 58 of the terms that Ontario parents and speech-language pathology students run into most often. Each entry is short and in plain language, with links to longer guides and free tools where they exist. Terms are listed alphabetically.

A note on sources: definitions of language domains and disorders follow the American Speech-Language-Hearing Association (ASHA) Practice Portal unless another source is named. Ontario-specific terms follow the Audiology and Speech-Language Pathology Act, 1991, the College of Audiologists and Speech-Language Pathologists of Ontario (CASLPO) and ontario.ca.

A to C

AAC (augmentative and alternative communication)

Any method that supplements or replaces spoken language, including gestures, manual signs, picture boards, letter boards and speech-generating devices or apps. ASHA describes AAC as augmentative when it adds to existing speech and alternative when it stands in for speech that is absent or not functional. Research summarized by ASHA does not support the idea that AAC stops children from talking.

Articulation

The physical movements of the lips, tongue, jaw and soft palate that produce speech sounds. An articulation error is a problem with producing a specific sound, such as a lisp on “s”.

Articulation disorder

A speech sound disorder in which a child has difficulty physically producing one or more sounds, past the age when most children have them. Crowe and McLeod (2020) report the ages by which 90% of American English-speaking children produce each consonant; the free speech sound checker is built on that data.

Audiologist

A regulated health professional who assesses hearing and balance and fits hearing aids and other devices. In Ontario, audiologists are registered with CASLPO alongside speech-language pathologists, and “audiologist” is a protected title under the same Act.

Babbling

Repeated consonant-vowel syllables such as “bababa” or “mamama” that typically appear in the second half of the first year. Babbling is a common item on milestone checklists because its absence by 12 months is a usual reason to ask for a hearing test and a speech and language referral. The milestone checklist covers this stage.

Bilingual (dual language) development

Learning two or more languages at once or in sequence. Speech-language pathologists assess bilingual children in all their languages where possible, because a delay that shows up in only one language is usually a sign of exposure, not a disorder. See the guide to bilingual children and speech delay.

Brown’s stages

Five stages of early grammatical development described by Roger Brown in 1973, each defined by a range of mean length of utterance rather than by age. The full counting rules and stage table are in the guide to MLU and Brown’s stages.

CASLPO

The College of Audiologists and Speech-Language Pathologists of Ontario, the provincial regulator. It registers speech-language pathologists and audiologists, sets practice standards, runs a public register and investigates complaints. Anyone using the title speech-language pathologist in Ontario must appear on the CASLPO Public Register.

CDA (communicative disorders assistant)

Support personnel, usually with a college graduate certificate, who carry out therapy activities planned by a speech-language pathologist or audiologist. CDAs are not regulated in Ontario, cannot use the protected titles and must work under the supervision of a registrant who stays responsible for the care. Speech-Language & Audiology Canada uses the broader term “communication health assistant”.

CETP exam

The Canadian Entry to Practice Exam for audiology and speech-language pathology. It is a competency-based, multiple-choice national exam administered by Speech-Language & Audiology Canada on behalf of provincial regulators. CASLPO has required it for registration since April 1, 2021, with a maximum of three attempts. See how to become a speech-language pathologist in Ontario.

Childhood apraxia of speech (CAS)

A neurological speech sound disorder in which the brain has difficulty planning and programming the movements for speech, even though muscle strength is normal. ASHA notes that children do not grow out of CAS but can improve with speech-language services. Inconsistent errors and difficulty with longer words are common signs. See signs of childhood apraxia of speech.

Children’s Treatment Centre

An Ontario community agency that provides rehabilitation services, including speech-language pathology, to children and youth with disabilities. Children’s Treatment Centres deliver School-Based Rehabilitation Services and, in many regions, host the Preschool Speech and Language Program. They serve children up to age 19, or 21 if still in school.

Cluttering

A fluency disorder in which speech sounds fast, irregular and jumbled, with collapsed syllables and many “normal” disfluencies. ASHA groups cluttering with stuttering under fluency disorders, but the two are different and can occur together.

Consonant cluster

Two or three consonants in a row with no vowel between them, such as “st” in “stop” or “spl” in “splash”. Clusters are often reduced in early speech (“top” for “stop”), and cluster reduction is one of the most common phonological processes.

Cycles approach

A treatment approach for children with many phonological patterns and low intelligibility. Each target pattern is worked on for a short cycle and then rotated, rather than drilled to mastery, on the idea that gradual exposure across patterns mirrors typical development. ASHA lists it among evidence-based phonological approaches.

D to F

Developmental language disorder (DLD)

A language disorder that is not explained by another condition such as hearing loss, autism or a brain injury. The CATALISE consensus led by Bishop and colleagues (2017) recommended the term DLD to replace “specific language impairment”. DLD affects understanding, talking or both, and persists into school age.

Disfluency

Any break in the smooth flow of speech, including repetitions, prolongations, blocks, revisions and fillers such as “um”. Everyone is disfluent sometimes. Speech-language pathologists distinguish typical disfluencies from stuttering-like disfluencies when assessing a young child. See stuttering in toddlers and preschoolers.

Dynamic assessment

A test-teach-retest approach in which the clinician observes how quickly a child learns a new skill with support. ASHA recommends it as a way to separate language difference from language disorder, which matters for bilingual children and for children with little experience of formal testing.

Dysarthria

A group of speech disorders caused by weakness, slowness or poor coordination of the speech muscles after a neurological injury or condition. ASHA describes it in terms of abnormal strength, speed, range or steadiness of movement. It is different from childhood apraxia of speech, where the muscles are strong but planning is affected.

Expressive language

The ability to put thoughts into words, signs or writing. It includes vocabulary, sentence structure and the ability to tell a story. ASHA pairs it with receptive language, and a child can be stronger in one than the other.

Fluency

The smoothness, rate and effort of speech. A fluency disorder, such as stuttering or cluttering, interrupts that flow.

I to L

IEP (Individual Education Plan)

A written plan describing the special education programs, accommodations and services a school board will provide for a student. Under Ontario’s special education policy, an IEP must be developed for every student identified as exceptional by an Identification, Placement and Review Committee, and may be written for other students who need support. Speech-language pathologists on school teams often contribute goals and accommodations.

Intelligibility

How much of a child’s speech a listener understands. A common rule of thumb is that strangers understand about half of what a two-year-old says, three-quarters at age three and nearly all by age four. The intelligibility estimator lets parents try a rough version of this at home.

Intelligibility in Context Scale

A seven-item parent questionnaire developed by Sharynne McLeod and colleagues. Parents rate how well different listeners, from parents to strangers, understand the child. It is available free in many languages and is widely used as a screening and outcome measure.

Joint attention

Two people sharing focus on the same object or event, for example a baby following a parent’s point and then looking back at the parent. It is an early social-communication skill that supports word learning.

Language sample

A recording and transcript of a child’s spontaneous talk, usually during play or conversation, that the clinician analyzes for vocabulary, grammar, sentence length and errors. Most protocols use 50 to 100 utterances. The MLU calculator accepts a typed sample and counts morphemes using Brown’s rules.

Late talker

A toddler whose expressive vocabulary is behind expectations, with no other diagnosed delay. ASHA uses the term late language emergence for children aged two to four. Common referral triggers in Ontario are no words by 18 months, or fewer than 50 words or no two-word combinations by 24 months. See late talker: what parents can do and the toddler word counter.

Lisp

An articulation error on “s” and “z” sounds. In a frontal lisp the tongue pushes between the teeth, producing something like “th”. In a lateral lisp air escapes over the sides of the tongue, producing a slushy sound. See lisp in children.

M to O

Mean length of utterance (MLU)

The average number of morphemes per utterance in a language sample. Miller and Chapman (1981) found that MLU rises by about 1.2 morphemes per year between about 18 months and five years, which makes it a useful index of grammar in young children. It is less informative after about age five.

Minimal pairs

Two words that differ by only one sound, such as “tea” and “key” or “sun” and “sung”. Minimal pairs are used in therapy to show a child that a sound change changes meaning. The free minimal pairs tool generates pairs for common phonological processes.

Morpheme

The smallest unit of language that carries meaning. “Cats” has two morphemes: “cat” and the plural “s”. Free morphemes stand alone (dog, run); bound morphemes attach to other words (-ing, -ed, un-).

Morphology

The study of how words are built from morphemes, including grammatical endings such as plural “s”, past tense “ed” and possessive “‘s”. ASHA groups morphology with phonology and syntax as the “form” of language.

Narrative

Telling or retelling a story or event in order, with characters, a problem and a resolution. Narrative skills develop through the preschool and early school years and are closely linked to reading comprehension.

Obligatory context

A point in an utterance where a grammatical morpheme is required by adult grammar. If a child says “two dog”, the plural “s” was obligatory and was omitted. Clinicians count correct use in obligatory contexts, often using a 90% criterion for mastery.

P to R

Parent-implemented intervention

Therapy in which the speech-language pathologist coaches parents to use language-building strategies in daily routines, rather than delivering all the practice in the clinic. A meta-analysis by Roberts and Kaiser (2011) found positive effects on the language skills of children aged 18 to 60 months. Ontario’s Preschool Speech and Language Program relies heavily on this model.

PCC (percentage of consonants correct)

The share of consonants a child produces correctly in a speech sample. Shriberg and Kwiatkowski (1982) introduced PCC as a severity measure, with bands of mild (above 85%), mild-moderate (65 to 85%), moderate-severe (50 to 65%) and severe (below 50%). The PCC calculator scores a transcribed sample.

Phoneme

A speech sound that distinguishes one word from another in a language. English has roughly 44 phonemes depending on the dialect. Phonemes are written between slashes, for example /k/.

Phonemic awareness

The ability to hear and play with the individual sounds in spoken words: knowing that “cat” starts with /k/, or that “cat” without /k/ is “at”. It is a strong predictor of early reading and is a subset of phonological awareness.

Phonological awareness

A broader skill than phonemic awareness that includes noticing rhymes, syllables, and the first and last sounds in words. It develops through the preschool years and is built by rhyming games, songs and shared reading. See reading books to build language.

Phonological process

A predictable pattern that simplifies adult speech, such as final consonant deletion (“ca” for “cat”) or fronting (“tat” for “cat”). All children use these patterns early; a phonological disorder is diagnosed when they persist past the usual age. See phonological processes explained.

Phonology

The sound system of a language: which sounds it uses and the rules for combining them. A phonological disorder affects patterns of sounds, while an articulation disorder affects the production of individual sounds.

Pragmatics

The social use of language: taking turns, staying on topic, adjusting to the listener and using eye contact, gestures and tone. ASHA calls pragmatics the “use” component of language.

Preschool Speech and Language Program (PSL)

Ontario’s free, publicly funded speech and language service for children from birth until they start school. Families self-refer with no doctor’s referral and no diagnosis required. Local lead agencies deliver the program, often through SmartStart Hubs. See how to get speech therapy in Ontario.

Prosody

The melody of speech: stress, rhythm, intonation and pacing. Unusual prosody is one feature clinicians listen for when assessing childhood apraxia of speech.

Receptive language

Understanding language: following directions, learning word meanings and understanding questions and stories. Receptive skills usually run ahead of expressive skills, and a receptive delay is treated as more significant than an expressive delay on its own.

S to V

SAC (Speech-Language & Audiology Canada)

The national professional association for speech-language pathologists, audiologists and communication health assistants. Membership is voluntary. SAC administers the CETP exam on behalf of regulators and runs a voluntary certification program whose members may use the designation S-LP(C). SAC certification does not grant the right to practise; only provincial regulators such as CASLPO do.

SBRS (School-Based Rehabilitation Services)

Speech-language pathology, occupational therapy and physiotherapy delivered in publicly funded Ontario schools by Children’s Treatment Centres. In most regions, SBRS covers articulation, motor speech, fluency and voice, while school board speech-language pathologists handle language and literacy.

Screening

A brief check that decides whether a fuller assessment is needed. A screening does not diagnose. Online checklists and the free tools on this site are informational, not screenings in the clinical sense.

Semantics

Word meanings and the relationships between them: vocabulary, categories, opposites and figurative language. ASHA calls semantics the “content” of language.

Speech-language pathologist (SLP)

A regulated health professional with a master’s degree who assesses and treats speech, language, voice, fluency, social communication and swallowing across the lifespan. In Ontario, “speech-language pathologist”, “speech therapist” and abbreviations such as SLP are protected titles under section 8 of the Audiology and Speech-Language Pathology Act, 1991. See how to check if a speech-language pathologist is registered in Ontario.

Speech sound disorder

ASHA’s umbrella term for any difficulty with perceiving, producing or mentally representing speech sounds, covering both articulation and phonological disorders. At school entry, roughly 11 to 12% of children have one. See the speech sound development chart.

Standardized assessment

A published test given and scored the same way for every child, with scores compared with a norming sample of the same age. Standard scores and percentiles come from these tests. ASHA advises combining them with language samples, parent report and dynamic assessment, especially for bilingual children.

Stimulability

Whether a child can produce a sound correctly when given a model and cues, even if they do not yet use it in words. Stimulable sounds are often expected to emerge on their own, and the finding helps clinicians choose targets.

Stuttering

A fluency disorder marked by repetitions of sounds or syllables, prolongations and blocks, often with tension or struggle. Many preschoolers go through a period of disfluency; a speech-language pathologist considers how long it has lasted, family history, tension and the child’s own awareness when deciding on treatment.

Syntax

The rules for ordering words into phrases and sentences, including questions, negatives and complex sentences with “because” or “when”. Syntax grows rapidly between ages two and five, which is what MLU tracks.

Telepractice

Speech-language pathology delivered by secure video or other telecommunication technology. ASHA defines it as a mode of service delivery, not a separate service, and it can be used alone or alongside in-person sessions. See virtual speech therapy for kids.

Utterance

A unit of spoken language, roughly one sentence or one thought, separated from the next by a pause or a change in intonation. Dividing a transcript into utterances is the first step in calculating MLU.

Voice disorder

A problem with pitch, loudness or vocal quality, such as persistent hoarseness. In children it is often linked to vocal strain from shouting. Speech-language pathologists assess voice, usually alongside an ear, nose and throat physician.

How to use this glossary

If a report or a school meeting uses a term that is not here, ask the clinician to define it; clear explanation is part of their job. Students preparing for the CETP exam can pair this list with the MLU calculator and PCC calculator to practise the measures behind the terms. Parents with a current concern can start with the guide on when to see a speech-language pathologist.