to speak extemporaneously

He can extemporize on any of a number of subjects.

to sing, or play on an instrument, composing the music as one proceeds; improvise.

to do or manage something in a makeshift way.

to make or devise extempore.

Music . to compose offhand; improvise.

verb

plan , prepare , read , rehearse

verb

ad-lib , dash out , devise , do offhand , improvisate , invent , knock off * , make up , play by ear , toss off , fake