Asperger syndrome (AS), also known as Asperger's syndrome, Asperger disorder (AD) or simply Asperger's, is an autism spectrum disorder (ASD) that is characterized by significant difficulties in social interaction and nonverbal communication, alongside restricted and repetitive patterns of behavior and interests. It differs from other autism spectrum disorders by its relative preservation of linguistic and cognitive development. Although not required for diagnosis, physical clumsiness and atypical (peculiar or odd) use of language are frequently reported. The diagnosis of Asperger's was eliminated in the 2013 fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and replaced by a diagnosis of autism spectrum disorder on a severity scale.