Meaning

noun an evil supernatural being

noun a cruel wicked and inhuman person

noun someone extremely diligent or skillful

originFrom Middle English demon, a borrowing from Medieval Latin dēmōn, daemōn (“lar, familiar spirit, guardian spirit”), from Ancient Greek δαίμων (daímōn, “dispenser, god, protective spirit”). Displaced native Old English sċucca and Old English þyrs. Doublet of daimon.

Etymology from Wiktionary, CC BY-SA 3.0