| Abbreviation | Definition |
|---|---|
| SWIFT | South Wales Integrated Fast Transit |
| SWK | Super Wide Kellner |
| SWSL | Supplemental Weather Service Location |
| SWVA | South Western Vehicle Auctions |
| SYB | Short Yellow Bus |
| SYE | Slip Yoke Eliminator |
| SZC | Sheik Zayed Air Navigation Centre |
| SZJ | Single Zone Journey |
| SZL | Single Zone License |
| SZMC | Shenzhen Metro Company |
| T | Toll |
| T/O | Train Operator |
| TA | Time of Arrival |
| TA | Traction Avant |
| TA | Traffic Assistant |
| TA | Traffic Assistant (obselete) |
| TA | Train Assistant |
| TA | Trans American |
| TA | True Airspeed |
| TA | Turbo Air |