| uneffusive(adjective, modest, nervous, humble, hesitant) |
| unlikely(uncertain, doubtful, unsure) |
| unpoised(adjective, uncertain, nervous, meek, insecure) |
| unselfassured |
| unselfconfident |
| unselfreliant |
| unserviceable(adjective, unreliable, insecure, treacherous, incalculable) |
| unsocial(adjective, modest, nervous, humble, hesitant) |
| unstable(loose, uncertain, nervous, doubtful, unreliable) |
| untrusty(adjective, false, uncertain, nervous, dishonest) |
| up for grabs(expression, adjective, idiom, uncertain, nervous) |
| up in the air(expression, idiom, uncertain, nervous, insecure) |
| uptight(uncertain, nervous, insecure, unsure, self-doubting) |
| vacillating(uncertain, nervous, shy, doubtful, fearful) |
| wavering(uncertain, nervous, shy, doubtful, fearful) |
| weak(uncertain, nervous, shy, doubtful, fearful) |
| wimpy(adjective, uncertain, nervous, doubtful, shaky) |
| wobbly(uncertain, nervous, doubtful, insecure, unsure) |
| wonky(adjective, unreliable, insecure, treacherous, incalculable) |
| adulterine(fickle, untrustworthy, unprincipled) |