The story
Pseudo-loan from Ancient Greek, derived from νεκρός (nekrós, “dead”) + νόμος (nómos, “law”) + εἰκών (eikṓn, “image”), literally “an image of the law of the dead”. Coined by American writer H. P. Lovecraft. By surface analysis, necro- + -nomicon.
Etymology from Wiktionary, CC BY-SA 4.0.