| on-the-scene |
| by ear(expression, adjective, free, fake, informal) |
| immediate(adjective, free, informal, prompt, casual) |
| improv(adjective, free, fake, informal, casual) |
| improvisatory(adjective, free, fake, informal, casual) |
| improviso(adjective, free, fake, informal, casual) |
| on-site |
| on impulse(expression, adjective, free, fake, informal) |
| accounted for(expression, adjective, present, near, nearby) |
| ad-lib(adjective, free, fake, casual, impulsive) |
| ad hoc(expression, adjective, free, casual, unrehearsed) |
| ad lib(expression, adjective, free, informal, casual) |
| at first glance(expression, idiom, free, informal, casual) |
| at hand(expression, adjective, adverb, present, nearby) |
| attendant(adjective, adverb, present, near, nearby) |
| automatic(adjective, free, informal, casual, impulsive) |
| autoschediastic(adjective, free, fake, casual, impulsive) |
| available(adjective, adverb, present, attendant, nearby) |
| casual(adjective, free, informal, impulsive, unprepared) |
| existent |