Accommodations Changes or adjustments that help meet a person’s individual needs.

Aggressive behavior Hostile or violent behavior, including hitting others, destroying property, or throwing tantrums. Aggression is among the most common challenges reported by parents of children and adolescents with autism.

Allergy A reaction by the immune system to something that does not bother most other people, such as certain foods, pollen or animals.

American Psychiatric Association An organization of psychiatrists working together to ensure humane care and effective treatment for all persons with mental illness.

Americans with Disabilities Act (ADA) U.S. law that ensures rights of persons with disabilities with regard to employment and other issues.

Angelman syndrome A genetic disorder causing developmental delays and neurological problems, often accompanied by seizures. Children often display hyperactivity, small head size, sleep disorders and movement and balance disorders.

Antecedent A verbal or physical stimulus, such as a command or request. The first in the three-step process used in Applied Behavior Analysis (ABA).

Anticonvulsant A type of drug used to prevent or stop seizures or convulsions; also called antiepileptic.

Anxiety Strong feelings of worry or fear about everyday activities. Anxiety disorder affects an estimated 30% of individuals with autism.

Applied Behavior Analysis (ABA) A style of teaching using series of trials to shape desired behavior or response. Skills are broken into small components and taught the individual through a system of reinforcement.

Asperger syndrome A developmental disorder, no longer used in the DSM-5, on the autism spectrum defined by impairments in communication and social development and by repetitive interests and behaviors, without a significant delay in language and cognitive development. The DSM-5 indicates that individuals with a “well-established diagnosis” of this condition “should be given the diagnosis of autism spectrum disorder.”

Assisted communication device A tool that helps you communicate with others. Examples include picture cards and electronic tablets that speak words that you type.

Attention deficit hyperactivity disorder (ADHD) A disorder that affects approximately 1 in 5 children with autism. Symptoms include chronic problems with inattention, impulsivity and hyperactivity.

Audiologist A professional who diagnoses and treats individuals with hearing loss or balance problems.

Augmentative and alternative communication (AAC) Methods of communication for people who can’t use speech (talking) to communicate; examples include sign language and using a computer for speech.

Autism Speaks Autism Treatment Network (ATN) A collaboration of Autism Speaks and some of the finest children’s hospitals and academic institutions in North America, specializing in multi-disciplinary medical care for children with autism.

Autism Spectrum Disorder (ASD) Also called autism. A condition characterized by a broad range of challenges with social skills, repetitive behaviors, and speech and nonverbal communication.

Autism-risk genes Specific genes that have been found to increase the risk of autism.

Autistic A term that many people who meet the criteria for ASD have adopted to describe their differences.


Babbling One of the first ways a baby communicates. Involves stringing together vowels and consonants such as “bababa” or “dadada”.

Baseline data Measurement of a behavior before an intervention is begun. Progress is measured by comparing current behavior to baseline data.

Behavioral intervention An intervention focused on increasing positive behavior and limiting challenging behavior, such as Applied Behavior Analysis.

Biomedical interventions A range of treatment methods that address underlying medical conditions and biological processes, such as the gastrointestinal system, diet and nutrition, immune function and sleep.

Board-certified behavior analyst (BCBA) A professional specialized in autism, certified and trained to write, implement and monitor a child’s individualized ABA program.

Body language Nonverbal communication through physical movements and gestures.

Brain abnormalities Differences in typical features of the brain such as structure or functioning.


Casein A protein found in milk, used in forming the basis of cheese and as a food additive.

Childhood disintegrative disorder A disorder in which development begins normally in all areas, physical and mental. At some point between 2 and 10 years of age, the child loses previously developed skills. The child may lose social and language skills and other functions, including bowel and bladder control. The diagnosis is no longer used in DSM-5, but DSM-5 indicates that individuals with a “well-established diagnosis” of this condition “should be given the diagnosis of autism spectrum disorder.”

Chromosomal (single-gene) disorder A disorder caused by a single gene. Examples include Fragile X syndrome, cystic fibrosis and muscular dystrophy.

Chromosome-15 duplication syndrome A chromosome abnormality that occurs when an extra (duplicate) copy of the genetic material located on chromosome-15 is present in each cell.

Chromosome An organized package of DNA found in the nucleus of the cell. Chromosomes are the physical carrier of genes.

Chronic constipation An ongoing condition of having fewer than three bowel movements per week.

Cognitive deficit An inclusive term to describe any characteristic that acts as a barrier to mental skills such as acquiring information and knowledge.

Cognitive skills Any mental skills that are used in the process of acquiring knowledge; these skills include reasoning, perception and judgment.

Colitis An inflammation of the large intestine.

Comorbid conditions Different conditions that occur in the same person.

Complete Blood Count (CBC) A lab test reporting number of white blood cells, red blood cells, platelets, hemoglobin, hematocrit and other values reflecting overall blood health.

Compulsions Deliberate repetitive behaviors that follow specific rules, such as those pertaining to cleaning, checking or counting. In young children, restricted patterns of interest may be an early sign of compulsions.

Computed Axial Tomography A medical test that examines organs by scanning with X rays and using a computer to construct series of cross-sectional scans. Called “CAT” scan.

Consequence A result or effect of an action or condition. Consequences are used in behavioral therapy and can include positive reinforcement of the desired behavior or no reaction for incorrect responses.

Convulsions Whole body shaking that can sometimes be caused by epilepsy or seizure disorder.