← BackshareGuessextemporize/ɪkˈstɛmpəraɪz/verbTo speak or perform without preparation or rehearsal; to improvise.He can extemporize a song on the guitar in any key.During the power outage, we had to extemporize a game to pass the time.The speaker had to extemporize when her notes blew away.Synonymsimprovisead-libAntonymsrehearse