| Abbreviation | Definition |
|---|---|
| RN | regenerative nodule |
| RN | rehabilitation nurse |
| RN | rheumatoid nodule |
| RNCC | registered nursing care contribution |
| RNID | Royal National Institute for the Deaf (later Royal National Institute for Deaf People, now Action on Hearing Loss) |
| RNMH | Registered Nurse for the Mentally Handicapped (obsolete title) |
| RO | radiation oncologist |
| RO | reactive oxygen |
| RO | reflux oesophagitis |
| RO | relative odds |
| RO | renal oncocytoma |
| RO | renal osteodystrophy |
| RO | revenue out turn (!) |
| ROCRSC | Review of Central Returns Steering Committee |
| ROE | Regional Office for Europe |
| ROE | right otitis externa |
| ROHFT | Royal Orthopaedic Hospital Foundation Trust |
| ROI | range of interest |
| ROI | reactive oxygen intermediate |
| ROLE | Recognition Of Life Extinct |