| ANSI | American National Standards Institute |
|---|---|
| AFIP | Armed Forces Institute of Pathology |
| AHA | acetohydroxamic acid; acquired hemolytic anemia; acute hemolytic anemia; American Heart Association;... |
| AHI | active hostility index; Animal Health Institute; apnea-plus-hypopnea index |
| AIBS | American Institute of Biological Sciences |