Definitions

1. adjective

occurring or done without prior planning or preparation; impromptu

“The comedian’s extemporal joke brought the house down with laughter.”

2. noun

something that happens or is done without prior planning or preparation

“The extemporal nature of the event made it difficult to report on.”

3. adverb

in a manner that is impromptu or unplanned

“She delivered an extemporal speech to the crowd.”