| ad lib(expression, adjective, free, informal, casual) |
| by ear(expression, adjective, free, informal, casual) |
| improv(adjective, adverb, free, informal, casual) |
| ad hoc(adjective, free, informal, casual, snap) |
| at first glance(expression, idiom, free, informal, casual) |
| expedient(adjective, free, informal, casual, snap) |
| extemporary(adjective, free, casual, spontaneous, impromptu) |
| extempore(adjective, adverb, free, impromptu, unrehearsed) |
| gone off half-cocked(expression, adjective, idiom, violent, fast) |
| immediate(adjective, free, informal, casual, snap) |
| impromptu(adjective, adverb, free, unrehearsed, improvised) |
| improvisatory(adjective, free, informal, casual, snap) |
| improvised(adjective, adverb, free, offhand, impromptu) |
| improviso(adjective, free, informal, casual, snap) |
| informal(adjective, free, casual, snap, impromptu) |
| jamming(adjective, free, informal, casual, snap) |
| jump the gun(expression, adjective, idiom, violent, fast) |
| made-up(adjective, free, informal, snap, unrehearsed) |
| makeshift(adjective, adverb, free, informal, casual) |
| off the cuff(expression, adjective, idiom, free, unrehearsed) |