1. 即兴演出，临时插入（脚本或讲稿中没有的台词）
    If you ad-lib something in a play or a speech, you say something which has not been planned or written beforehand.

    e.g. He began comically ad-libbing a script...
           他即兴调侃起了一段剧本。
    e.g. He''s good at ad-libbing his way out of trouble...
           他善于为自己妙语解围。

2. 即兴（或临时插入）的台词
    An ad-lib is something which is said without having been planned or written beforehand.

    e.g. Every time I fluffed a line Lenny got me out of trouble with a brilliant ad-lib.
           每次我台词出错时，伦尼都通过机智的临场发挥帮我解围。

1. remark made spontaneously without prior preparation

    e.g. his ad-libs got him in trouble with the politicians

1. perform without preparation

    e.g. he extemporized a speech at the wedding

    Synonym: improviseimprovizeextemporizeextemporise

1. with little or no preparation or forethought

    e.g. his ad-lib comments showed poor judgment
           an extemporaneous piano recital
           an extemporary lecture
           an extempore skit
           an impromptu speech
           offhand excuses
           trying to sound offhanded and reassuring
           an off-the-cuff toast
           a few unrehearsed comments

    Synonym: extemporaneousextemporaryextemporeimpromptuoffhandoffhandedoff-the-cuffunrehearsed

2. said or done without having been planned or written in advance

    e.g. he made a few ad-lib remarks

    Synonym: spontaneousunwritten