| ad-lib(adjective, adverb, simple, natural, casual) |
| ad lib(expression, adjective, adverb, simple, informal) |
| automatic(adjective, simple, natural, casual, impulsive) |
| break loose(expression, adjective, simple, natural, casual) |
| by ear(expression, adjective, adverb, informal, snap) |
| casual(adjective, simple, natural, impulsive, willing) |
| down(adjective, simple, natural, casual, impulsive) |
| extemporaneous(adjective, simple, natural, casual, impulsive) |
| extempore(adjective, adverb, simple, natural, casual) |
| free(adjective, simple, natural, casual, impulsive) |
| free spirited(expression, adjective, simple, natural, casual) |
| from the hip(expression, adjective, idiom, simple, natural) |
| impetuous(adjective, simple, natural, casual, impulsive) |
| impromptu(adjective, adverb, simple, natural, casual) |
| improv(adjective, adverb, informal, snap, offhand) |
| improvised(adjective, adverb, simple, natural, casual) |
| impulsive(adjective, simple, natural, casual, willing) |
| inevitable(adjective, simple, natural, casual, impulsive) |
| instinctive(adjective, simple, natural, casual, impulsive) |
| involuntary(adjective, simple, natural, casual, impulsive) |