inexorable

a. [ L. inexorabilis: cf. F. inexorable. See In- not, and Exorable, Adore. ] Not to be persuaded or moved by entreaty or prayer; firm; determined; unyielding; unchangeable; inflexible; relentless; -- of people and impersonal forces; as, an inexorable prince or tyrant; an inexorable judge; the inexorable advance of a glacier. “Inexorable equality of laws.” Gibbon. “Death's inexorable doom.” Dryden. [ 1913 Webster ]

You are more inhuman, more inexorable,
O, ten times more than tigers of Hyrcania. Shak. [ 1913 Webster ]