| impromptu(adjective, adverb, free, offhand, unprepared) |
| ad lib(expression, adjective, free, informal, mock) |
| by ear(expression, adjective, free, fake, informal) |
| extempore(adjective, free, simple, fake, straightforward) |
| free(adjective, simple, fake, straightforward, casual) |
| improvisatory(adjective, free, fake, informal, casual) |
| improviso(adjective, free, fake, informal, mock) |
| makeshift(adjective, adverb, free, casual, impromptu) |
| offhand(adjective, adverb, free, casual, spontaneous) |
| on-the-spot(adjective, free, fake, informal, casual) |
| on impulse(expression, adjective, free, fake, informal) |
| spontaneous(adjective, free, simple, fake, informal) |
| tossed off(expression, adjective, free, informal, mock) |
| unpremeditated(adjective, free, casual, spontaneous, unprepared) |
| unprepared(adjective, free, casual, spontaneous, impromptu) |
| ad-lib(verb, adjective, adverb, make, fix) |
| off the cuff(expression, adjective, idiom, adverb, free) |
| spur-of-the-moment(adjective, free, casual, spontaneous, unprepared) |
| ad hoc(expression, adjective, free, casual, unrehearsed) |
| at first glance(expression, idiom, free, informal, casual) |