ex ‧ tem ‧ po ‧ rize BrE AmE ( also extemporise British English ) /ɪkˈstempəraɪz/ verb [intransitive] formal
to speak or perform without preparation or practice
—extemporization /ɪkˌstempəraɪˈzeɪʃ ə n $ -rə-/ noun [uncountable and countable]
ex ‧ tem ‧ po ‧ rize BrE AmE ( also extemporise British English ) /ɪkˈstempəraɪz/ verb [intransitive] formal
to speak or perform without preparation or practice
—extemporization /ɪkˌstempəraɪˈzeɪʃ ə n $ -rə-/ noun [uncountable and countable]
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012