Source : Webster's Revised Unabridged Dictionary (1913)

Obdurate \Ob"du*rate\, a. [L. obduratus, p. p. of obdurare to
   harden; ob (see Ob-)+ durare to harden, durus hard. See
   {Dure}.]
   1. Hardened in feelings, esp. against moral or mollifying
      influences; unyielding; hard-hearted; stubbornly wicked.

            The very custom of evil makes the heart obdurate
            against whatsoever instructions to the contrary.
                                                  --Hooker.

            Art thou obdurate, flinty, hard as steel, Nay, more
            than flint, for stone at rain relenteth? --Shak.

   2. Hard; harsh; rugged; rough; intractable. ``Obdurate
      consonants.'' --Swift.

   Note: Sometimes accented on the second syllable, especially
         by the older poets.

               There is no flesh in man's obdurate heart.
                                                  --Cowper.

   Syn: Hard; firm; unbending; inflexible; unyielding; stubborn;
        obstinate; impenitent; callous; unfeeling; insensible;
        unsusceptible.

   Usage: {Obdurate}, {Callous}, {Hardened}. Callous denotes a
          deadening of the sensibilities; as. a callous
          conscience. Hardened implies a general and settled
          disregard for the claims of interest, duty, and
          sympathy; as, hardened in vice. Obdurate implies an
          active resistance of the heart and will aganst the
          pleadings of compassion and humanity. --
          {Ob"du*rate*ly}, adv. -- {Ob"du*rate*ness}, n.

Obdurate \Ob"du*rate\, v. t.
   To harden. [Obs.]

Source : WordNet®

obdurate
     adj 1: stubbornly persistent in wrongdoing [syn: {cussed}, {obstinate},
             {unrepentant}]
     2: showing unfeeling resistance to tender feelings; "the
        child's misery would move even the most obdurate heart"
        [syn: {flinty}, {stony}]