implacable Synonyms

irreconcilable unappeasable relentless unyielding inexorable unrelenting steely pitiless stern stiff-necked stubborn steadfast severe ruthless rigid revengeful retaliatory resolute remorseless rancorous punitory tigerish tough unmourned unbendable unassuageable unabated unstoppable unforgiving brassbound unadaptable unbending wreakful vindictive vindicatory vengeful unmerciful unfeeling uncompromising unsparing unsympathetic persistent hardened hard grudgeful grim firm fierce ferric dogged