said or done without having been planned or written in advance; "he made a few ad-lib remarks"
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"
Unrehearsed, spontaneous act of speaking, performing, or otherwise improvising on-camera activity without preparation.
To improvise lines or speeches that are not part of the script.
Speech or action that has not been scripted or specially rehearsed
to make up a joke within a scripted show.