| Abbreviation | Definition |
|---|---|
| FNBDT | Future Narrow Band Digital Terminal |
| FNBDT | Future Narrow-Band Data Terminal |
| FNBVT | Future Narrow Band Voice Terminal |
| FNBVT | Future Narrow-Band Voice Terminal |
| FNC | Fabrique Nationale Carbine |
| FNC | Framework Nations Concept |
| FNCI | Forces Nouvelles de Côte d'Ivoire |
| FNG | Florida National Guard |
| FNMOD | Fleet Numerical Meteorological and Oceanographic Detachment |
| FNOC | Fleet Numerical Oceanographic Command |
| FNS | Foreign Nation Support |
| FNSI | Finding of No Significant Impact |
| FO | Falcon Office |
| FO | Fiber Optic |
| FO | Fiber Optics |
| FO | Flash Override |
| FO | Follow-on |
| FO | Force Operations |
| FO | Forward Observer |
| FO/FAC | Forward Observer/Forward Air Controller |