The phrase "not rehearsed" implies an element of spontaneity and authenticity in either a speech, performance, or action. Some synonymous phrases to describe spontaneity include off the cuff, improvisational, impromptu, ad-lib, and unrehearsed. An individual who speaks off the cuff relies on their natural ability to think on the spot and use their knowledge without prior reflection. The term improvisational is often used in the context of music or acting where performers use their creativity to produce a new and unique piece of work. Ad-lib is another similar phrase that suggests spontaneity and quick thinking. Unrehearsed is another term that implies an element of unexpectedness and unpreparedness.