ex·tem·po·rize (also extemporise British English) /ɪkˈstempəraɪz/ verb [intransitiveI] formal TALK/MAKE A SPEECHto speak or perform without preparation or practice 临场[即席]讲话；即兴表演
—extemporization /ɪkˌstempəraɪˈzeɪʃən $ -rə-/ noun [countableC, uncountableU]