It is the D. "Disorder". The implication in that one word is "sick, damaged, mentally ill"., I actually NEED the "autistic" label, but most of the people I've met (including professionals) seem to think it's a terrible thing.
A better designation might be Autisim Spectrum Diversity. It encompasses the idea that a.s.d. is different but allows for autisim to be one end of the spectrum of normal.