definition of
[harden]

[1] #1 harden v. [indurate] become hard or harder; "The wax hardened". wn

[2] #2 harden v. [indurate] make hard or harder; "The cold hardened the butter". wn

[3] #3 harden v. [temper] harden by reheating and cooling in oil; "temper steel". wn

[4] #4 harden v. [season] make fit; "This trip will season even the hardiest traveller". wn

[5] #5 harden v. [inure, indurate] cause to accept or become hardened to; habituate; "He was inured to the cold". wn