| Abbreviation | Definition |
|---|---|
| FJST | Fiji Summer Time |
| FJT | Fiji Time |
| FKST | Falkland Islands Summer Time |
| FKT | Falkland Island Time |
| FN | Fore Noon |
| FNT | Fernando de Noronha Time |
| GA | Greenwich Atomic (name used in UK for UTC prior to 1964) |
| GALT | Galapagos Time |
| GAMT | Gambier Time |
| GBT | Great British Time |
| GCT | Greenwich Civil Time (suggested replacement name, in 1925, for GMT) |
| GET | Georgia Standard Time |
| GFT | French Guiana Time |
| GILT | Gilbert Island Time |
| GMAT | Greenwich Mean Astronomical Time (UT - 12 hours) |
| GMT | Greenwich Mean Time |
| GMT | Greenwich Mean Time (replaced by Universal Time in 1928, and UTC in 1960) |
| GST | Greenwich Sidereal Time |
| GST | Guam Standard Time [UTC + 1000] |
| GST | Gulf Standard Time |