adj. 25B6; adjective
he was hardened to the violence he had seen : INURED, desensitized, deadened; accustomed, habituated, acclimatized, used.
a hardened criminal : INVETERATE, seasoned, habitual, chronic, compulsive, confirmed, dyed-in-the-wool; incorrigible, incurable, irredeemable, unregenerate.
the silos are hardened against air attack : STRENGTHENED, fortified, reinforced, toughened.