Lewis & Short

Magontĭăcum, i, n., a city of Germany, on the Rhine, the modern Mayence, Tac. H. 4, 15; 24 sq.; called Mogontĭă-cum, Eutr. 7, 8; 9, 7; Magontĭăcus, i, f., Amm. 15, 11, 8; and Maguntia, ae, f., Venant. Fort. Carm. 9, 9, 1.