To anneal or toughen by a process of gradually heating and cooling; SYN. temper.
to heat and cool metal gradually to temper.
strengthen; temper, especially by subjecting to great heat and slow cooling.

1. To prepare by chemical processing in order to preserve.
2. To provide a cure for, make healthy again; SYN. heal.

1. To become hard or harder.
2. To make hard or harder.

To make hard, callous or unfeeling; harden.

1. Abnormal hardening or thickening of tissue.
2. The act of making something harder (firmer or tighter or more compact).
3. The process of becoming hard or solid by cooling or drying or crystallization; SYN. solidifying, solidification, set.