Definition of: harden

(här′dən) v.t.
1. To make hard or harder; make solid.
2. To make unyielding, pitiless, or indifferent.
3. To strengthen or make firm in any element of character, disposition, etc.
4. To make tough, strong, or hardy; inure.
—v.i.
5. To become hard.
6. In commerce: a To become higher, as prices, b To become stable. [<ON harthna]