The Collaborative International Dictionary of English v.0.48:

Undevised \Undevised\
   See devised.

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "undevised":
   ad-lib, caught napping, caught off balance, caught short,
   extemporaneous, extemporized, haphazard, hasty, impromptu,
   improvised, inadvertent, makeshift, precipitate, rough-and-ready,
   snap, surprised, taken aback, taken by surprise, taken unawares,
   tripped up, unarranged, unbegun, unconcocted, uncontrived,
   undeliberated, undesigned, unhatched, unintended, unmade,
   unmanufactured, unorganized, unplanned, unpremeditated, unprepared,
   unprimed, unpurposed, unready, unstudied, unthought