Pronunciation: (im'pru-vīz"), [key]
—v., -vised, -vis•ing.
1. to compose and perform or deliver without previous preparation; extemporize: to improvise an acceptance speech.
2. to compose, play, recite, or sing (verse, music, etc.) on the spur of the moment.
3. to make, provide, or arrange from whatever materials are readily available: We improvised a dinner from yesterday's leftovers.
to compose, utter, execute, or arrange anything extemporaneously: When the actor forgot his lines he had to improvise.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.