Merriam-Webster Collegiate Dictionary - extemporaneous

 adjective  Etymology: Late Latin extemporaneus, from Latin ex tempore  Date: 1673  1.  a.  (1) composed, performed, or uttered on the spur of the moment ; impromptu an ~ comment  (2) carefully prepared but delivered without notes or text  b. skilled at or given to ~ utterance  c. happening suddenly and often unexpectedly and usually without clearly known causes or relationships a great deal of criminal and delinquent behavior is…~ — W. C. Reckless  2. provided, made, or put to use as an expedient ; makeshift an ~ shelter  • ~ly adverb  • ~ness noun