Meaning

noun a manual of black magic (for invoking spirits and demons)

originBorrowed from French grimoire, a variant of grammaire, from Old French gramaire (“grammar; grimoire; conjurer, magician”), from Latin grammatica (“grammar; philology”), from grammaticus (“relating to grammar, grammatical”), from Ancient Greek γρᾰμμᾰτῐκός (grămmătĭkós, “knowing one's letters; concerned with textual criticism”), from γράμμα (grámma, “that which is drawn or written; letter; book,…

Etymology from Wiktionary, CC BY-SA 3.0