INEXORABLE
adamant, adamantine, inexorable, intransigent
(adjective) impervious to pleas, persuasion, requests, reason; “he is adamant in his refusal to change his mind”; “Cynthia was inexorable; she would have none of him”- W.Churchill; “an intransigent conservative opposed to every liberal tendency”
grim, inexorable, relentless, stern, unappeasable, unforgiving, unrelenting
(adjective) not to be placated or appeased or moved by entreaty; “grim determination”; “grim necessity”; “Russia’s final hour, it seemed, approached with inexorable certainty”; “relentless persecution”; “the stern demands of parenthood”
Source: WordNet® 3.1
Etymology
Adjective
inexorable (comparative more inexorable, superlative most inexorable)
Impossible to prevent or stop; inevitable. [from mid 16th c.]
Synonyms: implacable, ineluctable, inescapable, unpreventable, unrelenting, unstoppable, Thesaurus:inevitable
Antonym: exorable
Unable to be persuaded; relentless; unrelenting. [from mid 16th c.]
Antonym: exorable
Adamant; severe.
Antonym: exorable
Source: Wiktionary
In*ex"o*ra*ble, a. Etym: [L. inexorabilis: cf. F. inexorable. See In-
not, and Exorable, Adore.]
Definition: Not to be persuaded or moved by entreaty or prayer; firm;
determined; unyielding; unchangeable; inflexible; relentless; as, an
inexorable prince or tyrant; an inexorable judge. "Inexorable
equality of laws." Gibbon. "Death's inexorable doom." Dryden.
You are more inhuman, more inexorable, O, ten times more than tigers
of Hyrcania. Shak.
Source: Webster’s Unabridged Dictionary 1913 Edition