obdurate (adj.)

• adamant
• asleep
• benumbed
• bony
• brazen
• callous
• calloused
• case-hardened
• cold
• coldhearted
• concrete
• conscienceless
• corneous
• dead
• deadened
• dense
• dogged
• dour
• dull
• firm
• flinty
• fundamentalist
• granitelike
• granitic
• hard
• hard-bitten
• hard-boiled
• hard-nosed
• hardened
• hardhearted
• heartless
• hidebound
• horny
• immovable
• impenitent
• inexorable
• inflexible
• insensate
• insensible
• insensitive
• insentient
• insolent
• inured
• iron
• ironclad
• ironlike
• mulish
• muscle-bound
• numb
• numbed
• obstinate
• obtuse
• orthodox
• osseous
• procrustean
• puritanic
• relentless
• resistant
• resistive
• rigid
• rigorous
• rockbound
• rocklike
• rocky
• seared
• shameless
• solid
• steely
• stiff
• stiff-necked
• stonelike
• stony
• stonyhearted
• straightlaced
• straitlaced
• stubborn
• thick-skinned
• tough
• unbending
• unblushing
• uncompassionate
• uncompromising
• unemotional
• unfeeling
• unmelted
• unmerciful
• unnatural
• unperceptive
• unrelenting
• unrepentant
• unresponsive
• unsympathetic
• untouched
• unyielding