Ghoul, or ghul, is an Arabic word and was a beast that hung around in graveyards and was meant to devour or seize corpses, and ghul meant seize. So what was this strange cadaver-devouring creature, this chewer of corpses, as Joyce would have called it? Was it a thing of myth? A kink in the Middle Eastern imagination?
No. A ghoul is just a cat. Apparently*, they're rather problematic in graveyards. So ghoulish is simply feline.
*I was told this by an ethnographic friend of mine, but he's got a PHD so I believe every word he says.