- daemon, dæmon (these spellings are generally only found for the senses of "inner spirit" and "divinity of Greek mythology")
- (countable)} A demon is an evil spirit.
- (countable) A demon is a fallen angel or satanic being; a false god.
- (countable) A demon is a person's inner spirit or genius, a daimon.
- (countable) A demon is a flaw in a person's character.
- The demon of stupidity haunts me whenever I open my mouth.