de·mon /ˈdimən/
  惡棍,惡魔,妖怪,精力過人的人
  De·mon n.
  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 intermediate 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.
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  demon
       n 1: one of the evil spirits of traditional Jewish and Christian
            belief [syn: devil, fiend, daemon, daimon]
       2: a cruel wicked and inhuman person [syn: monster, fiend,
          devil, ogre]
       3: someone extremely diligent or skillful; "he worked like a
          demon to finish the job on time"; "she's a demon at math"