im ‧ pro ‧ vise /ˈɪmprəvaɪz/ BrE AmE verb [intransitive and transitive]
[ Date: 1800-1900 ; Language: French ; Origin: improviser , from Italian , from improvviso 'sudden' ]
1 . 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.
2 . 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.
3 . 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 /ˌɪmprəvaɪˈzeɪʃ ə n $ ɪmˌprɑːvə-/ noun [uncountable and countable]