skills gained by a developing child, which should be achieved by a given age. Examples of such milestones include smiling by six weeks and sitting unsupported by eight months. Failure to achieve a particular milestone by a given age is indicative of *developmental delay. See table.
A severe, chronic disability which is attributable to a mental or physical impairment or combination of mental and physical impairments; is manifested before the person attains the age of 22; 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 of independent living, economic self-sufficiency; and reflects the person’s need for a combination and sequence of special, interdisciplinary or generic care treatments or services which are of lifelong or extended duration and are individually planned and coordinated.... developmental disability
any one of a group of conditions in infancy or childhood, that are characterized by delays in biologically determined psychological functions, such as language. They are more common in males than females and tend to follow a course of disability with gradual improvement. They are classified into pervasive conditions, in which many types of development are involved (e.g. *autism), and specific disorders, in which the disability is an isolated problem (such as *dyslexia).... developmental disorder