| Abbreviation | Definition |
|---|---|
| ER | external resistance |
| ER | extreme resistance |
| ER | oestrogen receptor. See ER |
| ERCP | Endoscopic Retrograde CholangeoPancreatography |
| ERG | electroretinography |
| ERG | ergonovine |
| ERG | ergosterol |
| ERG | External Reference Group |
| ERMA | emergency response management arrangements |
| ERMA | This term got 53 hits on 06.11.2011, and thus appears to have been retired from active use. Shrewsbury and Telford Hospital NHS Trust reported in May 2011, that ERMA has been stood down since 11th Feb |
| ERT | emergency room thoracotomy |
| ERT | endogenous reverse transcription |
| ERT | enzyme replacement therapy |
| ERT | esophageal radionuclide transit |
| ERT | estrogen replacement treatment |
| ERT | external (beam) radiotherapy |
| ES | educational supervisor |
| ES | electroshock |
| ES | emergency service |
| ES | employment service |