| A1 | aortic first sound |
|---|---|
| AFA | acromegaloid facial syndrome; advanced first aid; alcohol-formaldehyde-acetic [fixative] |
| AI | accidental injury; accidentally incurred; adiposity index; aggregation index; allergy and immunology... |
| 'Greek letter alpha' | angular acceleration; first [carbon atom next to the carbon atom bearing the active group in organic... |
| C1a | activated first component of complement |