Example : 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.

Synonyms : ad-lib, extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, unrehearsed