improvisatory
adjective uk/ˌɪm.prə.vaɪˈzeɪ.tər.i/ us/ˌɪm.prəˈvaɪ.zə.tɔːr.i/
（演讲、表演等）即兴的
(of speech or music) done or performed without having been planned exactly, making something up as it is being performed
an improvisatory dance/song 即兴舞蹈／歌曲
The music allows for improvisatory variation. 这首乐曲允许即兴变奏。
his improvisatory collaboration with director André Gregory 他与导演安德烈·格里高利的即兴合作