1 to make, do, or manage sth without preparation, using what you have 临时凑合: If you're short of teachers today you'll just have to improvise (= manage somehow with the people that you've got). 今天老师不够的话，你要将就一下了。

2 to play music, speak or act using your imagination instead of written or remembered material 即兴演奏、讲演或行动；临时创作: It was obvious that the actor had forgotten his lines and was trying to improvise. 那个演员显然忘了台词，在当场发挥呢。 ➔improvisation /ˌɪmprəvaɪˈzeɪʃn; US ɪmˌprɒvəˈzeɪʃn ||; ɪmˌprɑvəˈzeʃən/ noun [C,U]