harden

(härˈdn)

1. To make hard or harder.
2. To enable to withstand physical or mental hardship.
3. To make unfeeling, unsympathetic, or callous: “To love love and not its meaning hardens the heart in monstrous ways” (Archibald MacLeish).
4. To make sharp, as in outline.
5. To protect (nuclear weapons) by surrounding with earth or concrete.

1. To become hard or harder.
2. To rise and become stable. Used of prices.
3. To become inured.