1. (

• harden ,
• indurate

) become hard or harder; "The wax hardened" ;

2. (

• harden ,
• indurate ,

) make hard or harder; "The cold hardened the butter" ;

3. (

• temper ,
• harden ,

) harden by reheating and cooling in oil; "temper steel" ;

4. (

• season ,
• harden ,

) make fit; "This trip will season even the hardiest traveller" ;

5. (

• inure ,
• harden ,
• indurate ,

) cause to accept or become hardened to; habituate; "He was inured to the cold" ;