With little or no preparation or forethought. Synonyms: extemporaneous, extemporary, extempore, impromptu, off-the-cuff, offhand, offhanded, unrehearsed. "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"