unforgiving Synonyms

inexorable relentless unappeasable grim unrelenting stern uncharitable unbending uncompromising tough tight stony iron-fisted spiteful severe ruthless rigid unsympathetic unfeeling unkind uncompassionate inhumane sadistic barbaric unpitying unyielding wreakful vindictive vindicative vengeful unsparing unmerciful revengeful remorseless hard forbidding flinty diamantine deadly cruel cold-blooded callous brutal bowelless avengeful adamantine hard-hearted harsh heartless critical