| Abbreviation | Definition |
|---|---|
| AAAS | Achalasia Addisonianism Alacrima Syndrome |
| AAAS | Alacrima Achalasia Addisonian Syndrome |
| ABDS | Athabaskan Brainstem Dysgenesis Syndrome |
| ACIS | Acquired Cellular Induration Syndrome |
| ACOS | asthma COPD overlap syndrome |
| ACSIS | Acute Coronary Syndrome Israeli Survey |
| ADS | Acquired Demyelinating Syndrome |
| ADSC | Adult Down Syndrome Center |
| AGS | advanced girth syndrome |
| AGS | Aicardi Goutieres Syndrome |
| AHDS | Acute Haemorrhagic Diarrhoea Syndrome |
| AHDS | Acute Hemorrhagic Diarrhea Syndrome |
| AHDS | Allan Herndon Dudley Syndrome |
| AHFS | Acute Heart Failure Syndrome |
| AHUS | Atypical Haemolytic Uraemic Syndrome |
| AHUS | Atypical Hemolytic Uremic Syndrome |
| AIDS | Acquired Immune Deficiency Syndromes |
| AIDS | Acquired Immuno Deficiency Syndrome |
| AIDS | Acquired Immuno Disease Syndrome |
| AIWS | Alice In Wonderland Syndrome |