- a few unrehearsed comments.
- a witty impromptu must not sound premeditated.
- an extemporaneous piano recital.
- an extemporary lecture.
- an extempore skit.
- an impromptu speech.
- an off-the-cuff toast.
- he spoke ad lib.
- his ad-lib comments showed poor judgment.
- offhand excuses.
- trying to sound offhanded and reassuring.