| UHMWPE | Ultra-high molecular weight polyethylene. |
| ULPA | Ultra-low penetration air (filtration). |
| Ultraviolet protection factor (UPF) | "A measure of the amount of protection against ultraviolet radiation to human skin provided by an item of clothing. UPF is similar in concept to the sun protection factor (SPF) which is used to categorise sun creams and lotions. However, SPF is more preci |
| Ultraviolet stability (geotextiles) | The ability of a geotextile to retain strength upon exposure to ultraviolet light over a specified period. |
| Unit production systems | "An advanced apparel manufacturing system in which a single garment is progressed through a sequence of operations. Using a unit production system, a garment is automatically transported via a computer-controlled overhead hanging system, which has been er |
| UPS | See unit production systems. |
| Uptwisting | A system of twisting one or more yarns by withdrawing them over-end from a rotating package. Uptwisting forms the second stage in two-stage twisting. |