Define developmental disability.

Developmental disability is a relatively recent term, and many people erroneously believe it to be synonymous with cognitive disability. However, it is a broader term that includes not only cognitive disabilities but also a variety of other conditions that occur before age 22 and hinder development. These conditions include infantile autism, cerebral palsy, and some cases of dyslexia (a learning disability).
The Rehabilitation, Comprehensive Services, and Developmental Disabilities Act (PL 95-602 ) of 1978 defines developmental disability as follows: Developmental disability means a severe, chronic disability of a person which is attributable to a mental or physical impairment or combination of mental and physical impairment and:

is manifest before twenty-two years of age
is likely to continue indefinitely
results in substantial functional limitations in three or more of the following areas of major life activity: self-care, receptive and expressive language, learning, mobility, self-direction, capacity for independent living, and economic self-sufficiency
reflects the person's need for a combination and sequence of special, interdisciplinary, or generic care, treatment or other services which are of lifelong or extended duration and individually planned and coordinated.