unappeasable

from WordNet (r) 3.0 (2006)

unappeasable
    adj 1: 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}, {unappeasable}, {unforgiving}, {unrelenting}]

from The Collaborative International Dictionary of English v.0.48

Unappeasable \Unappeasable\
   See {appeasable}.

from Moby Thesaurus II by Grady Ward, 1.0

62 Moby Thesaurus words for "unappeasable":
      a hog for, acquisitive, all-devouring, avaricious, avenging, avid,
      bottomless, coveting, covetous, devouring, esurient, gluttonous,
      gobbling, grabby, grasping, greedy, grudgeful, hoggish, implacable,
      insatiable, insatiate, irreconcilable, limitless, mercenary,
      merciless, miserly, money-hungry, money-mad, mortal, omnivorous,
      overgreedy, piggish, punitive, punitory, quenchless, rancorous,
      rapacious, ravening, ravenous, relentless, retaliatory, revanchist,
      revengeful, ruthless, slakeless, sordid, swinish, unappeased,
      unflinching, unquenchable, unrelenting, unsated, unsatisfiable,
      unsatisfied, unslakeable, unslaked, unyielding, venal, vengeful,
      vindicatory, vindictive, voracious