形容詞 extemporaneous:

1. with little or no preparation or forethought
   同義詞：ad-lib, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed

ex.tem.po.ra.ne.ous

adj.（形容詞）
Carried out or performed with little or no preparation; impromptu:
即興的：毫無準(zhǔn)備的或稍作準(zhǔn)備就執(zhí)行或表演的；即興的：
例句：
an extemporaneous piano recital.
即興鋼琴獨(dú)奏

Prepared in advance but delivered without notes or text:
不用講稿的：事前有所準(zhǔn)備而不帶筆記或本文的：
例句：
an extemporaneous speech.
不用講稿的演講

Skilled at or given to unrehearsed speech or performance:
善于即興講話的：擅長(zhǎng)于或傾向于即興演說或即興表演的：
例句：
an accomplished extemporaneous speaker.
一位高明的即席演講者

Provided, made, or adapted as an expedient; makeshift:
臨時(shí)的，權(quán)宜的：作為權(quán)宜之計(jì)而提供的、制作的或使用的；權(quán)宜的：
例句：
an extemporaneous policy decision.
一個(gè)權(quán)宜的政策決定

來源：
From Late Latin extempor3neus
源自 后期拉丁語 extempor3neus
from Latin ex tempore * see extempore
源自 拉丁語 ex tempore *參見 extempore

【引伸】
extem.porane.ity
extem.pora.neously
adv.（副詞）
extem.pora.neousness
n.（名詞）
<參考詞匯><同義詞>extemporaneous,extemporary,extempore,impromptu,offhand,unrehearsed,unpremeditated,ad-libThese adjectives mean spoken, performed, done, or composed with little or no preparation or forethought.Extemporaneous, extemporary, and extempore most often apply to discourse, as a public speech, that is delivered without the assistance of a written text, though it may have been planned in advance:
這些形容詞的意思是未經(jīng)準(zhǔn)備或構(gòu)思而演講的、表演的、進(jìn)行的或譜寫的。Extemporaneous，extemporary 和 extempore 常適用于演講，如公共演說， 雖然這可能經(jīng)過提前籌劃但演講時(shí)卻不需書面材料的幫助：
例句：
an extemporaneous address;
即興演說；

例句：
an extemporary lecture;
即興講座；

例句：
an extempore skit.
即興小品。

Impromptu even more strongly suggests action or expression that comes on the spur of the moment in response to an unforeseen need:
Impromptu 更強(qiáng)烈地表現(xiàn)對(duì)意料之外的需要所做出的相應(yīng)的動(dòng)作或表現(xiàn)：
例句：
an impromptu speech;
即席講話；

例句：
an impromptu dinner.
便飯。

Offhand implies not only spontaneity but also a casual or even cavalier manner:
Offhand 不但表示自發(fā)的，也表示不經(jīng)意的甚至漫不經(jīng)心的舉止的：
例句：
an offhand remark. What isunrehearsed is said or done without rehearsal or practice though not necessarily without forethought:
隨意的評(píng)論。 所謂unrehearsed ，就是未經(jīng)復(fù)述或練習(xí)就說或做的， 雖然沒有不構(gòu)思的必要：

例句：
a few unrehearsed comments.
未經(jīng)練習(xí)的評(píng)論。

Unpremeditated applies to action taken without prior thought or plan;often the term implies impulsiveness prompted by strong feeling:
Unpremeditated 表示未經(jīng)提前思考或計(jì)劃而采取的行動(dòng)；這個(gè)詞常表示在強(qiáng)烈情感的慫恿下而造成的沖動(dòng)：
例句：
asked an unpremeditated question. Something that isad-lib is spontaneous and improvised and therefore not part of a prepared script or score:
隨口提出一個(gè)問題。 ad-lib 的事物是自發(fā)產(chǎn)生的和即興而作的， 因而不是預(yù)先準(zhǔn)備的手稿或記錄的部分：

例句：
an ad-lib joke;
隨口開的玩笑；

例句：
an ad-lib solo.
即興的獨(dú)奏