DEFINITION: (adjective) Spoken, carried out, or composed with little or no preparation or forethought.
SYNONYMS: ad-lib, extemporaneous, extemporary, impromptu, off-the-cuff, offhand, offhanded, unrehearsed.
USAGE: The class performed an extempore skit that condensed the complex plot of Shakespeare's <i>Hamlet</i> into a single, 15-minute act.