| Abbreviation | Definition |
|---|---|
| TUa | Acute Toxicity Unit |
| TW | Tare Weight |
| TW | Tropical Weight |
| TWH | TeraWatt Hour |
| TYA | Thousand Years Ago |
| TYO | Total Yarn Quantity |
| U | Units |
| u. | unit(s) |
| U/L | Units per Liter |
| U/M | Unit of Measure |
| uA | MicroAmpere |
| UCS | Unit Coordinate System |
| UCS | Units Of Crack Susceptibility |
| UEQ | Microequivalents |
| UEQ/L | Microequivalents per Liter |
| ug/m3 | micrograms per cubic meter of air |
| UI | Unit International |
| UI | Unit Interval |
| UJE | Urban Junction East |
| UMS | Universal Measuring System |