Macro-Siouan Syllabification: (Mac·ro-Siou·an)Pronunciation: /ˌmakrōˈso͞oən/Definition of Macro-Siouan noun a proposed phylum of North American languages including the Siouan, Iroquoian, and Caddoan families and some others. adjective relating to the Macro-Siouan language phylum.
