Implacable
Pronunciation : Im*pla"ca*ble
Part of Speech : a.
Etymology : [L. implacabilis; pref. im- not + placabilis: cf. F. implacable. See Placable.]
Definition : 1. Not placable; not to be appeased; incapable of being pacified; inexorable; as, an implacable prince. I see thou art implacable. Milton. An object of implacable enmity. Macaulay.
2. Incapable of ebign relieved or assuaged; inextinguishable. [R.] O! how I burn with implacable fire. Spenser. Which wrought them pain Implacable, and many a dolorous groan. Milton.
Syn. -- Unappeasable; inexorable; irreconcilable; unrelenting; relentless; unyielding.
Source : Webster's Unabridged Dictionary, 1913