What most seem to agree on is that “Autism spectrum disorder (ASD) refers to a group of complex neurodevelopment disorders [1].”
Is a disorder a disease? While the terms are often used interchangeably by us laymen, the DSM-5 distinguishes the two [2].
[0] https://www.psychologytoday.com/us/blog/abcs-child-psychiatr...
[1] https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Educat...
[2] http://www2.hawaii.edu/~heiby/overheads_classification.html