unmoved by persuasion, pity, or tender feelings; stubborn; unyielding.
2.
stubbornly resistant to moral influence; persistently impenitent: an obdurate sinner.
Origin: 1400–50; late Middle English obdurat < Latin obdūrātus (past participle of obdūrāre to harden), equivalent to ob-ob- + dūr(us) hard + -ātus-ate1