ădămantĭnus — Lewis & Short
ădămantĭnus, a, um, adj., = a)dama/ntinos,
I hard as steel, etc., adamantine:
saxa,Lucr. 2, 447:
duritia,Plin. 37, 11, 73. —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.