...improvisar, to improvise, extemporize... 
Gustavo Adolfo Becquer 「Legends, Tales and Poems」
...They attend at public rejoicings, and at births, deaths, and marriages of great personages, upon which occasions they extemporize their songs according to circumstances...
Samuel White Baker 「In the Heart of Africa」
ランダム例文：
ailerons subtle gossamer
便利！手書き漢字入力検索
この漢字は何でしょう？？