| Abbreviation | Definition |
|---|---|
| AD | Acute Disorder |
| AD | ADenovirus |
| AD | Admitting Diagnosis |
| AD | Adult Disease |
| AD | After Death |
| AD | Alternating Days |
| AD | Alzheimer's Disease |
| AD | Aortic Diameter |
| AD | Arterial Device |
| AD | Attachment Device |
| AD | Attention Deficit |
| AD | Auditory Discrimination |
| AD | Auris Dexter (Right Ear) |
| ADA | Anterior descending artery |
| ADAA | Anxiety and Depression Association of America |
| ADAP | Adolescent Depression Awareness Program |
| ADC(s) | antibody-drug conjugates(s) |
| ADCC | Antibody Dependent Cell-mediated Cytotoxicity |
| ADCC | Antibody-Dependant Cellular Cytoxicity |
| ADD | Addiction |