| underscore | To emphasize, stress, or indicate the importance of something | |
| undermine | to weaken or damage something, especially gradually or insidiously | |
| uncultivated | Not cultivated; not prepared or used for growing crops or gardening | |
| unctuous | Excessively flattering or ingratiating; oily | |
| unconventional | Not based on or conforming to what is generally done or believed | |
| unconscionable | Not right or reasonable; unreasonably excessive | |
| unbridled | Uncontrolled; unconstrained | |
| unadorned | Not decorated with something to increase its beauty or distinction | |
| umbrage | offense or annoyance | |
| ubiquitous | Present, appearing, or found everywhere | |