| FEF | Forced Expiratory Flow |
|---|---|
| FEF | Frontal eye field |
| FEF(25-75) | forced expiratory flow |
| FEF25-75 | forced expiratory flow between 25 and 75% of vital capacity |
| FEH | Focal epithelial hyperplasia |
| FEHB | Federal Employee Health Benefits |
| FEHBP | Federal Employees Health Benefits Program |
| FEL | Familial erythrophagocytic lymphohistiocytosis |
| FEL | Free Electron Laser |
| FEL | Friend erythroleukaemia |