THESAURUS
remorseless
bowelless, callous, cruel, dog-eat-dog, flinty, griefless, hard, harsh, heartless, impenitent, implacable, inclement, inexorable, merciless, pitiless, regretless, relentless, ruthless, savage, shameless, sorrowless, unashamed, uncompassionate, uncompassioned, uncontrite, unfeeling, unforgiving, ungrieving, unmerciful, unpitiful, unpitying, unregretful, unregretting, unrelenting, unremitting, unremorseful, unrepentant, unrepining, unrueful, unsorrowful, unsorrowing, unsorry, unstoppable, unsympathetic, unsympathizing, unyielding, without mercy
ROGET THESAURUS
remorseless
Revenge
N
revenge, revengement, vengeance, avengement, avengeance, sweet revenge, vendetta, death feud, blood for blood retaliation, day of reckoning, rancor, vindictiveness, implacability, malevolence, ruthlessness, avenger, vindicator, Nemesis, Eumenides, revengeful, vengeful, vindictive, rancorous, pitiless, ruthless, rigorous, avenging, unforgiving, unrelenting, inexorable, stony-hearted, implacable, relentless,
remorseless, aeternum servans sub pectore vulnus, rankling, immitigable, manet ciratrix, manet alid mente repostum, dies irae dies illa, in high vengeance there is noble scorn, inhumanum verbum est ultio, malevolus animus abditos dentes habet, now infidel I have thee on the hip.
Impenitence
N
impenitence, irrepentance, recusance, lack of contrition, hardness of heart, seared conscience, induration, obduracy, impenitent, uncontrite, obdurate, hard, hardened, seared, recusant, unrepentant, relentless,
remorseless, graceless, shriftless, lost, incorrigible, irreclaimable, unreconstructed, unregenerate, unreformed, unrepented, unreclaimed, unatoned.