|Origin:||improviser, from Italian, from improvviso 'sudden'|
to do something without any preparation, because you are forced to do this by unexpected events:
I forgot to bring my notes, so I had to improvise.
to make something by using whatever you can find because you do not have the equipment or materials that you need:
There were no nappies, so we had to improvise with what we could find.
Annie improvised a sandpit for the children.
to invent music, words, a statement etc from your imagination, rather than planning or preparing it first:
I just started playing, and the other guys started improvising around me.
an improvised sketch
—improvisation noun [uncountable and countable]