Autism

 Any one of a group of disorders with an onset typically occurring during the preschool years and characterized by varying but often marked and persistent deficits in social communication and social interaction, including difficulties with social-emotional reciprocity, nonverbal communication behaviors, and social relationships, along with restricted and repetitive patterns of interests, behaviors, and/or activities.

ASD is now the official term used in DSM-5 and DSM-5-TR, where it encompasses and subsumes the disorders formerly known as autism, Asperger’s disorder, and childhood disintegrative disorder, which are no longer considered distinct diagnoses