Here are some synonyms for "extemporaneously":
* Impromptu
* Unscripted
* Off-the-cuff
* Ad-libbed
* Spontaneously
Here are some examples of how "extemporaneously" can be used in a sentence:
* The comedian delivered a hilarious stand-up routine extemporaneously, drawing laughter from the audience with his quick wit and off-the-cuff remarks.
* The musician played a beautiful piano piece extemporaneously, improvising a melody on the spot.
* The speaker was forced to speak extemporaneously after the planned presentation was cancelled due to a technical malfunction.
In essence, "extemporaneously" highlights the improvisational nature of an action or speech, emphasizing the lack of pre-planning and the ability to think and act on the fly.