The word "Improvisate" is often misspelled as "improvise." The correct spelling is with the ending "-ate," which indicates an action or state of being. The IPA phonetic transcription of Improvisate is /ɪmˈprɑvɪzˌeɪt/ which consists of five syllables, stress on the second syllable (im-PROV-i-zate). The word means to create or perform spontaneously without preparation or planning. It is often used in the context of music, theater, or comedy.
Unpremeditated.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.