ădămantĭnus, a, um, adj., = ἀδαμάντινος,
hard as steel , etc., adamantine : saxa, Lucr. 2, 447: duritia, Plin. 37, 11, 73, 189. —Hence poet., extremely hard , inflexible , invincible : clavi, Hor. C. 3, 24, 5: tunica, id. ib. 1, 6, 13: juga, Prop. 3, 9, 9; cf. aënus.