即兴创作用英文怎么讲？

即兴创作的英文是“improvised”： created and performed spontaneously or without preparation; impromptu.

例子："an improvised short speech"
一个即兴创作的短演讲。

这个单词也有凑合之意：
done or made using whatever is available; makeshift.
"we slept on improvised beds"