| Abbreviation | Definition |
|---|---|
| A | Agar |
| a | before (from Latin ante) |
| A.C. | after food (ante cibum) [Lat.] |
| A.C. | Ante Cibum (before meals) |
| A.M. | Ante Meridiem (take before noon) |
| AA | Of each (Ana) |
| AAA | Apply to Affected Area |
| AAAD,KJA | An Apple A Day, Keeps Jen Away |
| ABVD | Adriamycin, Bleomycin, Vinblatine and Dacarbazine |
| ACD(solution) | citric acid, sodium citrate dextrose |
| ACD(solution) | citric acid, sodium citrate & dextrose |
| ACMD | Advisory Council of Many Drugs |
| ACST | Acasti |
| ACT | airway clearance therapy |
| ACU | Acupuncture |
| AD | Auris Dextra (right ear) |
| AD | Up to .... |
| ADC(s) | antibody-drug conjugate(s) |
| ADFIN | Ad Finem (to the end) |
| ADMOV | Admove (apply) |