IDEA provides definitions of the 13 disability categories. Federal definitions guide how states define who is eligible for a free appropriate public education under IDEA. The definitions are as follows:
1. Autism
... a developmental disability significantly affecting verbal and nonverbal communication and social interaction as well as hyper sensory and hypo-sensory, generally evident during developmental stages, that adversely affects a child’s educational performance. Other characteristics often associated with autism are engaging in repetitive activities and movements, resistance to environmental change or change in daily routines, and unusual responses to sensory experiences. The term autism does not apply if the child’s educational performance is adversely affected primarily because the child has an emotional disturbance, as defined in #4 below. It also excludes Asperger and PDD.
2. Deaf-Blindness
... concomitant [simultaneous] hearing and visual impairments, the combination of which causes such severe communication and other developmental and educational needs that they cannot be accommodated in special education programs solely for children with deafness or children with blindness.
3. Deafness
.. a hearing impairment so severe that a child is impaired in processing linguistic information through hearing, with or without amplification, that adversely affects a child's educational performance.
4. Emotional Disturbance
... a condition exhibiting one or more of the following characteristics over a long period of time and to a marked degree that adversely affects a child’s educational performance:
(a) An inability to learn that cannot be explained by intellectual, sensory, or health factors.
(b) An inability to build or maintain satisfactory interpersonal relationships with peers and teachers.
(c) Inappropriate types of behavior or feelings under normal circumstances.
(d) A general pervasive mood of unhappiness or depression.
(e) A tendency to develop physical symptoms or fears
associated with personal or school problems. The term includes schizophrenia. The term does not apply to children who are socially maladjusted, unless it is determined that they have an emotional disturbance.
5. Hearing Impairment
.. an impairment in hearing, whether permanent or fluctuating, that adversely affects a child’s educational performance but is not included under the definition of “deafness.”
6. Intellectual Disabilities
...significantly below average general intellectual functioning, existing concurrently [at the same time] with deficits in adaptive behavior and manifested during the developmental period, that adversely affects a child’s educational performance.
7. Multiple Disabilities
... concomitant [simultaneous] impairments (such as mental retardation-blindness, mental retardation-orthopedic impairment), the combination of which causes such severe educational needs that they cannot be accommodated in special education programs solely for one of the impairments. The term does not include deaf-blindness.
8. Orthopedic Impairment
... a severe orthopedic impairment that adversely affects a child’s educational performance. The term includes impairments caused by a congenital anomaly, impairments caused by disease (e.g., poliomyelitis, bone tuberculosis), and impairments from other causes (e.g., cerebral palsy, amputations, and fractures or burns that cause contractures).
9. Other Health Impairment
... having limited strength, vitality, or alertness, including a heightened alertness to environmental stimuli, that results in limited alertness with respect to the educational environment, that—
(a) is due to chronic or acute health problems such as asthma, attention deficit disorder or attention deficit hyperactivity disorder, diabetes, epilepsy, a heart condition, hemophilia, lead poisoning, leukemia, nephritis, rheumatic fever, sickle cell anemia, and Tourette syndrome; and (b) adversely affects a child’s educational performance.
10. Specific Learning Disability
... a disorder in one or more of the basic psychological processes involved in understanding or in using language, spoken or written, that may manifest itself in difficulties with the ability to listen, think, speak, read, write, spell, or to do mathematical calculations. The term includes such conditions as perceptual disabilities, brain injury, minimal brain dysfunction, dyslexia, and developmental aphasia. The term does not include learning problems that are primarily the result of visual, hearing, or motor disabilities, mental retardation, emotional disturbance, or environmental, cultural, or economic disadvantage.
11. Speech or Language Impairment
... a communication disorder such as stuttering, impaired articulation, a language impairment, or a voice impairment that adversely affects a child’s educational performance.
12. Traumatic Brain Injury
... an acquired injury to the brain caused by an external physical force, resulting in total or partial functional disability or psychosocial impairment, or both, that adversely affects a child's educational performance. The term applies to open or closed head injuries resulting in impairments in one or more areas, such as cognition, language, memory, attention, reasoning, abstract thinking, judgment, problem solving, sensory, perceptual and motor abilities, psychosocial behavior, physical functions, information processing, and speech. The term does not apply to brain injuries that are congenital or degenerative, or to brain injuries induced by birth trauma.
13. Visual Impairment Including Blindness
... an impairment in vision that, even with correction, adversely affects a child’s educational performance. The term includes both partial sight and blindness.
Reference from: NICHCY, the National Dissemination Center for Children with Disabilities.