inexorable
adj.
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
adj.
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|an intransigent conservative opposed to every liberal tendency