n. (Abbr. PDD)
Any of several disorders, such as autism and Asperger's syndrome, characterized by severe deficits in many areas of development, including social interaction and communication, or by the presence of repetitive, stereotyped behaviors. Such disorders are usually evident in the first years of life and are often associated with some degree of mental retardation.
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
