(a.) Not merciful; indisposed to mercy or grace; cruel; inhuman; merciless; unkind.

barbarous bowelless brutal brutish callous calloused cold cold of heart coldblooded coldhearted cruel dog-eat-dog flinthearted flinty hard hard of heart hardened hardhearted harsh heartless inclement inexorable insensitive mean merciless obdurate pitiless relentless remorseless ruthless savage stonyhearted uncompassionate uncompassioned unfeeling unforgiving unkind unnatural unpitiful unpitying unremorseful unresponsive unsparing unsympathetic unsympathizing unyielding vicious without mercy