extempore

详细解释:a. 即席的, 当场的
ad. 即席, 当场
n. 即席之作

英语解释：

形容词 extempore:

with little or no preparation or forethought同义词：ad-lib, extemporaneous, extemporary, impromptu, offhand, offhanded, off-the-cuff, unrehearsed