obdurate

About 0.36 uses per million words.

Meaning

1. adjective Stubbornly persistent, generally in wrongdoing; refusing to reform or repent.
2. adjective Physically hardened, toughened.
3. adjective Hardened against feeling; hard-hearted.
4. verb To harden; to obdure. .mw-parser-output .defdate{font-size:smaller}

   (Can we add an example for this sense?)

Similar words

obstinate hardhearted unrepentant unregenerate heartless unregenerated cussed stony flinty stubborn

Often followed by

and in heart to as hearts than refusal resistance

Word family

obdurately obdurateness obduratenesses