improvisation

noun

1. (countable, uncountable)The act or art of composing and making music, poetry, and the like, extemporaneously

   “He played a quick improvisation on the keyboard.”

2. (countable, uncountable)That which is improvised; an impromptu.
3. (countable, uncountable)Musical technique, characteristic of blues music.
4. (countable, uncountable)The act of improvising, acting or going about something without planning ahead

   “The Ivorian is a player with such a liking for improvisation it does not usually look like he has any more idea than anyone else what he is going to do next, so it was an interesting choice.”