The Collaborative International Dictionary of English v.0.48:

Ghoulish \Ghoul"ish\, a.
   Characteristic of a ghoul; vampirelike; hyenalike.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ghoulish
    adj 1: suggesting the horror of death and decay; "morbid
           details" [syn: ghoulish, morbid]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "ghoulish":
   Mephistophelian, abominable, agape, agog, all agog, appalling,
   astounding, awe-inspiring, awesome, awful, barbaric, bloodthirsty,
   brutal, burning with curiosity, consumed with curiosity, cruel,
   curious, cursed, damnable, demoniac, demoniacal, demonic, demonish,
   demonlike, devil-like, devilish, diabolic, diabolical, dire,
   direful, disgusting, dread, dreaded, dreadful, execrable, fell,
   feral, ferocious, fiendish, fiendlike, formidable, ghastly,
   gossipy, grim, grisly, gruesome, hellish, hideous, horrendous,
   horrible, horrid, horrific, horrifying, infernal, inhuman,
   inquiring, inquisitive, interested, itchy, macabre, malign,
   merciless, monstrous, morbid, morbidly curious, ogreish, open-eyed,
   openmouthed, overcurious, pitiless, prurient, quizzical,
   redoubtable, ruthless, satanic, savage, schrecklich, scopophiliac,
   shocking, sick, supercurious, terrible, terrific, tremendous,
   ungodly, vicious, voyeuristic