improvise

动词 improvise:

1. perform without preparation
   同义词：improvize, ad-lib, extemporize, extemporise
2. manage in a makeshift way; do with whatever is at hand
   同义词：extemporize

1. If an actor forget his word, he have to improvise.
   演员要是忘记台词，那就只好即兴现编。
2. The pianist forgot his music and had to improvise (the accompaniment).
   弹钢琴的人把乐谱忘了，只好即兴伴奏。
3. As we've not got the proper materials, we'll just have to improvise.
   我们没有弄到合适的材料，只好临时凑合了。

im.pro.vise

v.（动词）
im.pro.vised,im.pro.vis.ing,im.pro.vis.es
v.tr.（及物动词）
To invent, compose, or recite without preparation.
即兴创作：无准备地发明、创作或者背诵
To make or provide from available materials:
临时提供，临时凑成：用可利用的材料做或提供：
例句：
improvised a dinner for the unexpected guests; improvise a makeshift tourniquet.
为不速之客准备晚餐；提供备用的止血带

v.intr.（不及物动词）
To invent, compose, recite, or execute something offhand.
即席创作; 即席表演：即兴地发明、创作、背诵或者制成某事物

来源：
French improviser
法语 improviser
from Italian improvvisare
源自 意大利语 improvvisare
from improvviso [unforeseen]
源自 improvviso [没有预见到的]
from Latin imprôvosus
源自 拉丁语 imprôvosus
in- [not] * see in-
in- [不] *参见 in-
prôvosus [past participle of] prôvidôre [to foresee] * see provide
prôvosus [] prôvidôre的过去分词 [预见] *参见 provide

【引伸】
im.provis.er
n.（名词）