Synonyms for Inexorable (same or very similar meaning)
WordNet sense 1 (not to be placated or appeased or moved by entreaty):
grim, relentless, stern, unforgiving, unrelenting, unappeasable
WordNet sense 2 (incapable of being placated):
implacable
WordNet sense 3 (impervious to pleas, persuasion, requests, reason):
adamant, adamantine, intransigent
WordNet sense 4 (incapable of change):
inflexible
From the ODE community, based on WordNet
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