| Abbreviation | Definition |
|---|---|
| AI | alcohol involvement |
| AI | allelic imbalance |
| AI | allergy and immunology |
| AI | allergy index |
| AI | aluminium |
| AI | aluminum |
| AI | alveolar interstitial |
| AI | ambulation index |
| AI | amelogenesis imperfecta |
| AI | amplification index |
| AI | amylase inhibitor |
| AI | An HIV-1 isolate used in HIV vaccine development, which belongs to clade B, the clade to which most HIV-1 found in America and Europe belongs. |
| AI | anal incontinence |
| AI | anchorage independent |
| AI | androgen independent |
| AI | angiogenesis inhibitor |
| AI | angiotensin I |
| AI | anisotropy index |
| AI | annual incidence |
| AI | antibody indices |