| U | the 21st letter of the Roman alphabet |
|---|---|
| U | a heavy toxic silvery-white radioactive metallic element |
| U | a nitrogen-containing base found in RNA (but not in DNA) and derived from pyrimidine |
| U | (chiefly British) of or appropriate to the upper classes especially in language use |
| U | a submersible warship usually armed with torpedoes |
| U | a rented car |
| U | nailed to underside of horse's hoof |
| U | complete reversal of direction of travel |
| U | the army of the United States of America |
| U | a division of the United States Army that is specially trained for guerrilla fighting |
| U | the executive and legislative and judicial branches of the federal government of the United States |
| U | North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean |