| abrupt(adjective, impulsive, rash, unthinking) |
| hit-or-miss(adjective, insignificant, irregular, senseless, planned) |
| incidental(adjective, chance, casual, random, haphazard) |
| indiscriminate(adjective, insignificant, irregular, senseless, planned) |
| precipitate(noun, adjective, impulsive, rash, unthinking) |
| unforeseen(adjective, chance, lucky, unintentional, accidental) |
| unstudied(adjective, free, simple, fake, natural) |
| extempore(adjective, free, simple, fake, informal) |
| impetuous(noun, adjective, simple, natural, casual) |
| impulsive(noun, adjective, simple, violent, natural) |
| involuntary(noun, adjective, simple, natural, casual) |
| spur-of-the-moment(noun, adjective, free, impulsive, spontaneous) |
| desultory(adjective, insignificant, irregular, senseless, planned) |
| purposeless(adjective, insignificant, useless, extensive, erratic) |
| snap(noun, adjective, free, informal, casual) |
| sudden(noun, adjective, impulsive, rash, unthinking) |
| unconscious(adjective, simple, natural, casual, impulsive) |
| ad lib(expression, adjective, free, casual, unrehearsed) |
| aimless(adjective, insignificant, casual, irregular, senseless) |
| improvised(adjective, free, simple, fake, informal) |