• ad-libber, extemporal, extemporaneous, extemporary, extempore, extemporizer
• to ad-lib, to extemporize, to fantasy, to improvise, to throw off
• ad-lib, extemporization, gag, impromptu, improvisation
• ad-lib, extemporal, extemporaneous, extemporary, extempore, impromptu, jury, makeshift, off-hand, scratch
• extemporaneously, extemporarily, impromptu, off the cuffs
• to make an extempore speech, to speak off the cuffs
• to extemporize on the organ