Harden
 

harden
verb1.become hard or harder; "The wax hardened"[ant: soften]2.make hard or harder; "The cold hardened the butter"[ant: soften]3.harden by reheating and cooling in oil; "temper steel"[syn: temper]4.make fit; "This trip will season even the hardiest traveller"[syn: season]5.cause to accept or become hardened to; habituate; "He was inured to the cold"[syn: inure]