Synonyms and related words :
bowelless, cruel, dog-eat-dog, flinty, griefless, hard, harsh, heartless, impenitent, inclement, inexorable, merciless, pitiless, regretless, relentless, remorseless, ruthless, shameless, sorrowless, unashamed, uncompassionate, uncompassioned, uncontrite, unfeeling, unforgiving, ungrieving, unmerciful, unpitiful, unpitying, unregretful, unregretting, unrepentant, unrepining, unrueful, unsorrowful, unsorrowing, unsorry, unsympathetic, unsympathizing, unyielding, without mercy