Synonyms and related words :
callous, hard, hardened, impenitent, insolent, obdurate, recidivist, recidivistic, recidivous, regretless, remorseless, unabject, unashamed, uncontrite, unembarrassed, unmelted, unregenerate, unregretful, unremorseful, unrepenting, unsoftened, unsorry, untouched