Below are the words that matched your query...
Unbanded
- not identified with a band; "an unbanded bird"  
Unbelted
- lacking a belt; "unbelted jackets are in this season"  
- undo the belt of; "unbelt your trousers"  
Unmalicious
- not malicious or spiteful  
Unexcelled
- not capable of being improved on  
Unexceeded
- not capable of being improved on  
Unsurpassed
- not capable of being improved on  
Unsurpassable
- not to be exceeded; "unsurpassable skill"; "unsurpassable standards of workmanship"  
Unicameral
- composed of one legislative body  
Unidirectional
- operating or moving or allowing movement in one direction only; "a unidirectional flow"; "a unidirectional antenna"; "a unidirectional approach to a problem"  
Unifacial
- having but one principal or specialized surface; "a primitive unifacial flint tool"