ex·tem·po·ri·za·tion /ɪkˌstɛmpərəˈzeʃən/
  即席作成,即席演說,即興之作
  Ex·tem·po·ri·za·tion n. The act of extemporizing; the act of doing anything extempore.
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  extemporization
       n : a performance given extempore without planning or
           preparation [syn: extemporisation, improvisation]