| Abbreviation | Definition |
|---|---|
| TYS | Tensile Yield Strength |
| U | Unplasticised |
| UAP | Uniunea Artistilor Plastici |
| UEV | Unsupported Expanded Vinyl |
| UF | Urea Formaldehyde resin |
| UHB | Ultra High Barrier |
| UHC | Unburned HydroCarbons |
| UHMW | Ultra High Molecular Weight (often applied to polyethylene) |
| UHP | Ultra High Pressure |
| UHX | Ultra-temperature Heat Exchanger |
| ULDPE | Ultra Low Density Polyethylene |
| UN | Universal Number |
| UPF | United Plastic Fabricating |
| UPVC | Unplasticised Poly Vinyl Chloride |
| UPVC | Unplasticized Poly Vinyl Chloride |
| UR | Universal Resin |
| USDOE | United States Department of Energy |
| UTS | Ultimate Tensile Strength |
| UTW | Ultra Thin Whitetopping |
| UV | Ultraviolet |