"improvisation" in the noun sense
1. improvisation
a creation spoken or written or composed extemporaneously (without prior preparation)
2. improvisation, temporary expedient
an unplanned expedient
3. extemporization, extemporisation, improvisation
a performance given extempore without planning or preparation
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License