Douglas Harper's Etymology Dictionary
1560s, from un- (1) "not" + appeasable. Related: Unappeasably.\n\nDesolate winds that cry over the wandering sea;\n
Desolate winds that hover in the flaming West;\n
Desolate winds that beat the doors of Heaven, and beat\n
The doors of Hell and blow there many a whimpering ghost;\n
O heart the winds have shaken, the unappeasable host\n
Is comelier than candles at Mother Mary's feet.\n
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[W.B. Yeats, "The Unappeasable Host," 1899]
Wiktionary
a. not able to be appeased or satisfied
WordNet
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" [syn: grim, inexorable, relentless, stern, unforgiving, unrelenting]
Usage examples of "unappeasable".
Or it needs the situation seen in Wales: her arms up and her unaffrighted eyes over the unappeasable growl.
And Bibbs turned at her direction to behold, amid a grove of tubbed palms, a "life-size," black-bearded Moor, of a plastic compositon painted with unappeasable gloss and brilliancy.
Darcy, that you hardly ever forgave, that your resentment once created was unappeasable.
But Hermann Kafka cannot be blamed for having become in his son's mind and art a myth, a core of overwhelming vitality and of unappeasable authority in relation to which one is hopelessly and forever in the wrong.