Lewis & Short

Grādīvus (once Grădīvus, Ov. M. 6, 427), i, m. [perh. from gradior, he who steps forth, marches out], a surname of Mars: (Numa) Salios item duodecim Marti Gradivo legit, Liv. 1, 20, 4: rex Gradive, Verg. A. 10, 542: Nymphas venerabar agrestes Gradivumque patrem, id. ib. 3, 35: Homericus, Juv. 13, 113: jure venis, Gradive, Ov. F. 2, 861; Juv. 2, 128; so absol.: Gradivus, id. ib. 3, 677; 5, 556; id. M. 14, 820; 15, 863.