obdurate

adj

1. Stubbornly persistent, generally in wrongdoing; refusing to reform or repent.

   “[…] sometimes the very custom of evil making the heart obdurate against whatsoever instructions to the contrary […]”

   “Art thou obdurate, flintie, hard as ſteele? / Nay more then flint, for ſtone at raine relenteth: […]”

   “[…] round he throws his baleful eyes That witness'd huge affliction and dismay Mixt with obdurate pride and stedfast hate:”

   “But custom maketh blind and obdurate The loftiest hearts.”

   “Late the next afternoon Tarzan and his Waziri returned with the first load of “belongings,” and when the party saw the ancient ingots of virgin gold they swarmed upon the ape-man with a thousand questions; but he was smilingly obdurate to their appeals—he declined to give them the slightest clew as to the source of his immense treasure.”

2. (obsolete)Physically hardened, toughened.

   “The past is obdurate for the same reason a turtle's shell is obdurate: because the living flesh inside is tender and defenseless.”

3. Hardened against feeling; hard-hearted.

   “I fear the gentleman to whom Miss Amelia's letters were addressed was rather an obdurate critic.”

verb

1. (obsolete, transitive)To harden; to obdure.