| FEF50 | forced expiratory flow at 50% of forced vital capacity |
|---|---|
| FEFV | forced expiratory flow volume |
| FF | degree of fineness of abrasive particles; fat-free; father factor; fecal frequency; fertility factor... |
| FFC | fixed flexion contracture; fluorescence flow cytometry; free from chlorine |
| FFF | degree of fineness of abrasive particles; field-flow fractionation; flicker fusion frequency |