| AHI | active hostility index; Animal Health Institute; apnea-plus-hypopnea index |
|---|---|
| aI | active ingredient |
| AI-CAH | autoimmune-type chronic active hepatitis |
| ALE | active life expectancy; allowable limits of error; amputated lower extremity |
| 'Greek letter alpha' | angular acceleration; first [carbon atom next to the carbon atom bearing the active group in organic... |