名詞 ad-lib:

1. remark made spontaneously without prior preparation

動詞 ad-lib:

1. perform without preparation
   同義詞：improvise, improvize, extemporize, extemporise

形容詞 ad-lib:

1. said or done without having been planned or written in advance
   同義詞：spontaneous, unwritten
2. with little or no preparation or forethought
   同義詞：extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed

副詞 ad-lib:

1. without advance preparation
   同義詞：ad lib, ad libitum, spontaneously, impromptu