Autism is a general term used to describe a constellation of complex developmental disorders known as Pervasive Developmental Disorders (PDD). PDD is like an umbrella with all of the other related disorders associated with it, falling underneath. Some people also refer to this as the Autism Spectrum.
Childhood Disintegrative Disorder
Pervasive Developmental Disorders – Not Otherwise Specified (PDD-NOS)
Autism is defined in the DSM-IV-TR as exhibiting at least six symptoms from the following three categories.
Marked impairment in verbal and non-verbal communication.
Engagement in repetitive or stereotypic movements, phrases, or movements of objects.