動(dòng)詞 improvise:

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

1. If an actor forget his word, he have to improvise.
   演員要是忘記臺(tái)詞，那就只好即興現(xiàn)編。
2. The pianist forgot his music and had to improvise (the accompaniment).
   彈鋼琴的人把樂(lè)譜忘了，只好即興伴奏。
3. As we've not got the proper materials, we'll just have to improvise.
   我們沒(méi)有弄到合適的材料，只好臨時(shí)湊合了。

im.pro.vise

v.（動(dòng)詞）
im.pro.vised,im.pro.vis.ing,im.pro.vis.es
v.tr.（及物動(dòng)詞）
To invent, compose, or recite without preparation.
即興創(chuàng)作：無(wú)準(zhǔn)備地發(fā)明、創(chuàng)作或者背誦
To make or provide from available materials:
臨時(shí)提供，臨時(shí)湊成：用可利用的材料做或提供：
例句：
improvised a dinner for the unexpected guests; improvise a makeshift tourniquet.
為不速之客準(zhǔn)備晚餐；提供備用的止血帶

v.intr.（不及物動(dòng)詞）
To invent, compose, recite, or execute something offhand.
即席創(chuàng)作; 即席表演：即興地發(fā)明、創(chuàng)作、背誦或者制成某事物

來(lái)源：
French improviser
法語(yǔ) improviser
from Italian improvvisare
源自 意大利語(yǔ) improvvisare
from improvviso [unforeseen]
源自 improvviso [沒(méi)有預(yù)見(jiàn)到的]
from Latin imprôvosus
源自 拉丁語(yǔ) imprôvosus
in- [not] * see in-
in- [不] *參見(jiàn) in-
prôvosus [past participle of] prôvidôre [to foresee] * see provide
prôvosus [] prôvidôre的過(guò)去分詞 [預(yù)見(jiàn)] *參見(jiàn) provide

【引伸】
im.provis.er
n.（名詞）