Impossible to appease or satisfy

unappeasable thirst and hunger.

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 ]

adjective

avid , edacious , gluttonous , greedy , omnivorous , rapacious , ravenous