- Unurgunite
- unusual number
- unusual plant
- unusual quantifiers
- unvarying
- unvoiced sound
- unvoised sound
- unvulcanized
- unweighted
- unweighted mean
- unwind
- unwinding
- unwinding protein
- unwrapping
- unwritten constitution
- unwritten law
- unyawed
- Unyielding Heroism
- UOE welded pipe process
- UOE焊管生产
- UOX
- UOX fuel
- UP
- Up
- up and down method