demon

noun

1. an evil spirit; devil or fiend.
2. an evil passion or influence.
3. a person considered extremely wicked, evil, or cruel.
4. a person with great energy, drive, etc.: He’s a demon for work.
5. a person, especially a child, who is very mischievous: His younger son is a real little demon.
6. daemon.
7. Australian Slang. a policeman, especially a detective.

adjective

8. of, pertaining to, characteristic of, or noting a demon.
9. possessed or controlled by a demon.

1. variant of demono- before a vowel: demonism.

noun

1. an evil spirit or devil
2. a person, habit, obsession, etc, thought of as evil, cruel, or persistently tormenting
3. Also called: daemon, daimon an attendant or ministering spirit; geniusthe demon of inspiration
4. 1. a person who is extremely skilful in, energetic at, or devoted to a given activity, esp a sporta demon at cycling
   2. (as modifier)a demon cyclist
5. a variant spelling of daemon (def. 1)
6. Australian and NZ informal, archaic a detective or policeman
7. computing a part of a computer program, such as a help facility, that can run in the background behind the current task or application, and which will only begin to work when certain conditions are met or when it is specifically invoked

n.

c.1200, from Latin daemon “spirit,” from Greek daimon “deity, divine power; lesser god; guiding spirit, tutelary deity” (sometimes including souls of the dead); “one’s genius, lot, or fortune;” from PIE *dai-mon- “divider, provider” (of fortunes or destinies), from root *da- “to divide” (see tide).

Used (with daimonion) in Christian Greek translations and Vulgate for “god of the heathen” and “unclean spirit.” Jewish authors earlier had employed the Greek word in this sense, using it to render shedim “lords, idols” in the Septuagint, and Matt. viii:31 has daimones, translated as deofol in Old English, feend or deuil in Middle English. Another Old English word for this was hellcniht, literally “hell-knight.”

The original mythological sense is sometimes written daemon for purposes of distinction. The Demon of Socrates was a daimonion, a “divine principle or inward oracle.” His accusers, and later the Church Fathers, however, represented this otherwise. The Demon Star (1895) is Algol.