| unconventional | Not based on or conforming to what is generally done or believed | |
| unctuous | Excessively flattering or ingratiating; oily | |
| uncultivated | Not cultivated; not prepared or used for growing crops or gardening | |
| undermine | to weaken or damage something, especially gradually or insidiously | |
| underscore | To emphasize, stress, or indicate the importance of something | |
| undulate | To move with a smooth wavelike motion | |
| uniform | Remaining the same in all cases and at all times; unchanging in form or character | |
| unkempt | Having an untidy or disheveled appearance | |
| unpretentiousness | The quality of being modest and not claiming to be important | |
| unpropitious | Not giving or indicating a good chance of success; unfavorable | |