THESAURUS
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
