| Term | Definition | Pronunciation |
| UA | urinalysis | |
| UE | upper extremity | |
| ul/o | scar, gums | |
| ulcer | A lesion on the surface of a organ or tissue, produced by the sloughing of inflammatory necrotic tissue. | |
| -ule | small, small one | |
| ulna | The inner and longer bone of the forearm. | |
| ulnar | Pertaining to the ulna, the long medial bone of the forearm. | |
| ultra- | beyond | |
| ultrasonography | The visualization of deep structures of the body by recording the reflections of ultrasonic pulses directed into the tissues. | |
| ultraviolet | Electromagnetic radiation that has shorter wavelengths than visible light. | |
| -um | structure, tissue | |
| umbilic- | umbilicus (navel) | |
| umbilical | Pertaining to the opening in the abdominal wall where the blood vessels from the placenta enter. | |
| umbilical cord | The flexible rope-like structure that connects a developing fetus to the placenta. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. | |
| umbilicus | The depression in the center of the abdominal wall where the umbilical cord entered in the fetus. Also called the navel. | |
| un- | not, reversal of an action | |
| unconsciousness | Abnormal loss of awareness of self and environment and lack of responsiveness to sensory stimuli. | |
| uncus | A hook-shaped structure. | |
| ung. | ointment | |
| ungu/o | nail | |
| ungual | Pertaining to the nails. | |
| unguis | A nail. | |
| uni- | one | |
| ur/o | urine | |
| uran/o | hard palate | |
| urea | A compound formed in the liver which is the major nitrogenous end product of protein metabolism | |
| uremia | Presence of excessive amounts of urea in the blood. May be a sign of renal disease or failure. | u-re´me-ah |
| -uresis | urination | |
| ureter | One of a pair of tubes that transports urine from the kidney pelvis to the urinary bladder. | |
| ureter/o | ureter | |
| ureteral | Pertaining to the ureter. | |
| ureterocele | A cystic dilatation of the end of a ureter as it enters into the urinary bladder. It may obstruct urine flow. | |
| ureterolithiasis | Formation of stones in the ureter. | |
| ureterostomy | Surgical creation of an external opening in the ureter for external drainage of the urine. | |
| urethr/o | urethra | |
| urethra | A tube that transports urine from the urinary bladder to the outside of the body in both the sexes. It also has a reproductive function in the male by providing a passage for sperm. | |
| urethral | Pertaining to the urethra. | |
| urethritis | Inflammation of the urethra, causing painful and difficult urination. | u″re-thri´tis |
| URI | upper respiratory infection | |
| -uria | urination | |
| urin/o | urine, urinary system | |
| urinalysis | Laboratory analysis of urine by chemical, physical, or microscopic means. | |
| urinary bladder | A muscular, membranous sac along the urinary tract that store urine until urination. | |
| urinary catheters | Catheters inserted into the urinary bladder or kidney for therapeutic or diagnostic purposes. | |
| urinary fistula | An abnormal passage in any part of the urinary tract between itself or with other organs. | |
| urination | Discharge of urine from the body. | |
| urine | The fluid containing waste products and water secreted by the kidneys, then stored in the urinary bladder until urination. | |
| urochesia | Passage of urine through the rectum. | |
| urolith | A stone in the urinary tract. | |
| urolithiasis | Formation of stones in any part of the urinary tract, usually in the kidney, urinary bladder or the ureter. | |
| urologic | Pertaining to urology. | |
| urology | A surgical specialty concerned with the study, diagnosis, and treatment of diseases of the urinary tract in both sexes, and the genital tract in the male. | |
| urothelium | The epithelial lining of the urinary tract. | |
| URT | upper respiratory tract | |
| urticaria | Hives, which are welts on the skin that often itch | ur″tĭ-ka´re-ah |
| US | ultrasound | |
| USP | United States Pharmacopeia | |
| ut. dict. | as directed | |
| uter/o | uterus | |
| uterine | Pertaining to the uterus. | |
| uterine prolapse | A condition where the uterus drops down into the vagina. | u´ter-in |
| uterus | The womb. A female reproductive organ located between the bladder and the rectum. | u´ter-us |
| UTI | urinary tract infection | |
| UV | ultraviolet | |
| UVA | ultraviolet A light | |
| uve/o | uvea | |
| uveal | Pertaining to the uvea. | |
| uveitis | Inflammation of the uvea. | |
| uvula | A fleshy extension at the back of the soft palate that hangs above the opening of the throat. | |