In the Oxford English Dictionary (OED), the standard headword and general term for the supreme evil spirit—encompassing of Devil . The OED defines devil primarily as: 1. In Christian, Jewish, and Islamic theology: The supreme spirit of evil; Satan. 2. In lower case ( devil ): An evil spirit; a demon. Key Etymology & Context in OED Origin: Enters Old English as dÄ“ofol , borrowed via Vulgar Latin ( diabolus ) from the Ancient Greek διάβολος ( diábolos ), meaning "accuser," "slanderer," or "adversary." Usage: When capitalized ( the Devil ), the OED classifies it as the proper designation for Satan/Lucifer. Uncapitalized ( devil ), it serves as a synonym for a demon, fiend, or evil spirit. In the Oxford English Dictionary (OED), power equivalency determines whether "devil" refers to a supreme sovereign power or a lesser subordinate e...