extemporaneous ek-stem-puh-RAY-nee-us, adjective:
1. Composed, performed, or uttered on the spur of the moment, or without previous study; unpremeditated; impromptu.
2. Prepared beforehand but delivered without notes or text.
3. Skilled at or given to extemporaneous speech.
4. Provided, made, or put to use as an expedient; makeshift.
Extemporaneous comes from Late Latin extemporaneous, from Latin ex tempore, “out of time,” therefore “immediately, at the very time the occasion arises.” It is related to temporary, “lasting for a limited time”; contemporary, “belonging to the same time” (con-, “with, together”); and tempo, “the rate or degree of movement in time.”