Implacable
Implacable , adjective
[Latin implacabilis; pref. im- not + placabilis: compare French implacable. See Placable.]
1.
Not placable; not to be appeased; incapable of being pacified; inexorable; as, an implacable prince.
I see thou art implacable.
An object of implacable enmity.
2.
Incapable of being relieved or assuaged; inextinguishable. [Rare]
O! how I burn with implacable fire.
Which wrought them pain
Implacable, and many a dolorous groan.