Marsaci
Could not find Marsacosque in Logeion dictionaries.
Marsacosque Proper-name noun: masculine accusative plural of Marsaci
Marsăci and Marsăcĭi, ōrum, m.,
- a people of Gallia Belgica.—Marsacii, Plin. 4, 15, 29, § 101: Marsaci, Tac. H. 4, 56.
Marsăcī (16) et -săcĭī, ōrum, m. , Marsaciens, peuple de la Belgique : Tac. H. 4, 56 ; Plin. 4, 101.