Correct spelling for the English word "prosateur" is [pɹəsɐtˈɜː], [pɹəsɐtˈɜː], [p_ɹ_ə_s_ɐ_t_ˈɜː] (IPA phonetic alphabet).
The word prosateur is derived from the French language. It comes from the Old French term proisier which means to speak. This term further evolved into proseur which referred to a writer or composer of prose. Eventually, proseur transformed into the modern French term prosateur, which roughly translates to prose writer or prosist.