| sporadic(adjective, capricious, motiveless) |
| strange(irregular, unpredictable, unreliable, irrelation) |
| stray(adjective, chance, irregular, unpredictable, unreliable) |
| temperamental(adjective, careless, unstable, unreasonable, changeable) |
| thoughtless(foolish, stupid, senseless, irrational, perverse) |
| uncompelled(voluntary, elective) |
| unexpected(adjective, careless, casual) |
| unforced(open, free, voluntary, elective) |
| unjustifiable(adjective, unreasonable, extreme, improper, stiff) |
| unmethodical(adjective, careless, casual, motiveless) |
| unnatural(irregular, unpredictable, unreliable, unconformity) |
| unorganized(adjective, careless, casual) |
| unplanned |
| unpremeditated(adjective, careless, chance, casual, random) |
| unreasoned(adjective, foolish, stupid, senseless, irrational) |
| unreasoning(irrational, perverse) |
| unthinking(careless, casual) |
| vacillating(adjective, changeable, indecisive, inconsistent, capricious) |
| vagarious(adjective, careless, unstable, unreasonable, irregular) |
| varying |