demon Meaning, Definition & Usage

  1. noun an evil supernatural being
    daemon; devil; daimon; fiend.
  2. noun a cruel wicked and inhuman person
    ogre; devil; monster; fiend.
  3. noun someone extremely diligent or skillful
    • he worked like a demon to finish the job on time
    • she's a demon at math

WordNet

De"mon noun
Etymology
F. démon, L. daemon a spirit, an evil spirit, fr. Gr. a divinity; of uncertain origin.
Definitions
  1. (Gr. Antiq.) A spirit, or immaterial being, holding a middle place between men and deities in pagan mythology.
    The demon kind is of an inmediate nature between the divine and the human. Sydenham.
  2. One's genius; a tutelary spirit or internal voice; as, the demon of Socrates. Often written dæmon.
  3. An evil spirit; a devil.
    That same demon that hath gulled thee thus. Shak.

Webster 1913