Pervasive developmental disorder, not otherwise specified (PDD-NOS). This mouthful of a diagnosis included most children whose autism was more severe than Asperger's syndrome, but not as severe as autistic disorder. Autistic disorder. This older term is further along the autism spectrum than Asperger’s and PDD-NOS.
PDD-NOS stands for Pervasive Developmental Disorder-Not Otherwise Specified. PDD-NOS was one of several previously separate subtypes of autism that were folded into the single diagnosis of autism spectrum disorder (ASD) with the publication of the DSM-5 diagnostic manual in 2013.