List of 426 Sets of Synonyms - How they Differ - Total of 2307 Words - 149

SYNONYMS: extemporaneous, extemporary, extempore, impromptu, offhand, unrehearsed, unpremeditated, ad-lib.
These adjectives mean spoken, performed, done, or composed with little or no preparation or forethought.

Extemporaneous, extemporary, and extempore most often apply to discourse, as a public speech, that is delivered without the assistance of a written text, though it may have been planned in advance: an extemporaneous address; an extemporary lecture; an extempore skit.
Impromptu even more strongly suggests action or expression that comes on the spur of the moment in response to an unforeseen need: an impromptu speech.
Offhand implies not only spontaneity but also a casual or even cavalier manner: an offhand remark.
What is unrehearsed is said or done without rehearsal or practice though not necessarily without forethought: a few unrehearsed comments.
Unpremeditated applies to action taken without prior thought or plan; often the term implies impulsiveness prompted by strong feeling: asked an unpremeditated question.
Something that is ad-lib is spontaneous and improvised and therefore not part of a prepared script or score: an ad-lib joke; an ad-lib solo.