1. extempore Extemporaneous, originally signifying of or from the time or occasion, has come to mean done or made with but little (if any) preparation, and is now chiefly applied to addresses of which the Synonyms: extemporaneous, extemporary, impromptu, offhand, extempore, improvised, unpremeditated Antonyms: elaborated, premeditated, prepared, read, recited, studied, written