Extemporizer is a word used to describe someone who speaks fluently without any preparation or forethought. There are a number of synonyms of extemporizer that can be used in place of it, such as extemporaneous speaker, impromptu speaker, off-the-cuff speaker, improvisational speaker, and spontaneous speaker. All these synonyms convey the same meaning as extemporizer and describe someone who can think on their feet, respond quickly, and formulate ideas without prior planning. In addition to these synonyms, other words that can be used are ad-lib speaker, impulsive speaker, and spur-of-the-moment speaker, all making reference to the ability to deliver a speech or talk on short notice.