in BRIT, also use 英国英语亦用 extemporise
- VERB 即席演说;即兴表演
If you extemporize, you speak, act, or perform something immediately, without rehearsing or preparing it beforehand.
- He completely departed from the text and extemporized in a very energetic fashion.
他完全脱稿,慷慨激昂地进行即席演说。