| UAO | Upper Airway Obstruction |
|---|---|
| UAP | Unstable Angina Pectoris |
| UAP | unlicensed assistive personnel |
| UAR | Upper airway resistance |
| UARS | Upper Airway Resistance Syndrome |
| UAS | Upstream Activating Sequence |
| UAS | Upstream Activation Sequence |
| UAS | Upstream Activator Sequence |
| UAS | upstream activation site |
| UASB | Upflow Anaerobic Sludge Blanket |