extemporary

1. with little or no preparation or forethought;

"his ad-lib comments showed poor judgment"

"an extemporaneous piano recital"

"an extemporary lecture"

"an extempore skit"

"an impromptu speech"

"offhand excuses"

"trying to sound offhanded and reassuring"

"an off-the-cuff toast"

"a few unrehearsed comments"