extemporary

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”