| Abbreviation | Definition |
|---|---|
| R/O | Rule Out |
| R66 | Relax |
| RA | Rubella Abortus |
| RAA | Renin Angiotensin-Aldosterone |
| RAA | Rhumatisme Articulaire Aigu (Acute Articular Rheumatism) |
| RAAS | Renin-Angiotensin-Aldosterone System |
| RABS | Rotation Around the Back Side |
| rACC | rostral Anterior Cingulate Cortex |
| RACK | Receptor Of Activated C Kinase |
| RAD | Radiate |
| RAD | Radiation Absorbed Dose |
| RAD | Reactive Airway Disease |
| RAD | Reactive Airways Disease |
| RAD | Reactive Attachment Disorder |
| RAE | Retinol Activity Equivalents |
| RAE | Right Atrial Enlargement |
| RAF | Rheumatoid Arthritis Factor |
| RAFS | Rotation Around the Front Side |
| RAG | Retinal Ablation Gene |
| RAI | RadioActive Iodine |