Lewis & Short

sagmārĭus, a, um, adj. [sagma], of or belonging to a pack-saddle (post-class.): equus, a pack-horse, Lampr. Heliog. 4; Aur. ap. Vop. Aur. 7, 7; cf.: caballus, mula, Isid. Orig. 20, 16, 5.