| uncontrolled(adjective, simple, natural, casual, impulsive) |
| unconventional(adjective, simple, easy, plain, straightforward) |
| unforced(adjective, simple, natural, casual, impulsive) |
| unfussy(adjective, simple, easy, plain, relaxed) |
| unintended(chance, unplanned, unpremeditated) |
| unintentional(adjective, simple, natural, chance, casual) |
| unofficial(adjective, simple, easy, plain, straightforward) |
| unpremediated(adjective, simple, natural, casual, impulsive) |
| unprompted(adjective, simple, natural, casual, impulsive) |
| unrestrained(adjective, simple, easy, plain, straightforward) |
| unsophisticated(adjective, simple, natural, casual, impulsive) |
| unwritten |
| up front(expression, adjective, simple, natural, casual) |
| urbane(adjective, simple, easy, plain, straightforward) |
| vamp |
| voluntary(adjective, simple, natural, casual, impulsive) |
| willing(adjective, simple, natural, casual, impulsive) |
| winging it(expression, free, casual, impulsive, unrehearsed) |
| without ceremony(expression, adjective, simple, straightforward, casual) |
| without preparation(expression, idiom, adverb, impromptu, extemporaneous) |