| Abbreviation | Definition |
|---|---|
| FJ | Fiji |
| FK | Falkland Islands (Malvinas) |
| FL | Floor |
| FLTS | FLaTS |
| FMM | Financial Management Manual |
| FMO | Field Maintenance Office |
| FO | Faroe Islands |
| FPI | Functional Process Improvement |
| FPO | Fleet Post Office |
| FR | Federal Register |
| FR | Flat Rate |
| FR | France |
| FRNT | Front |
| FSA | Forward Sortation Area |
| FSM | Flat Sorting Machine |
| FSO | Facilities Service Office |
| FSS | Flats Sequencing System |
| FX | France, Metropolitan |
| GA | Gabon |
| GD | Grenada |