demon

¹ American  

[dee-muhn] / ˈdi mən /

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.

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adjective

1. of, pertaining to, characteristic of, or noting a demon.

2. possessed or controlled by a demon.

demon- ² American  

1. variant of demono- before a vowel.

   demonism.

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demon British  

/ ˈdiːmən /

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; genius

   the demon of inspiration

4. 1. a person who is extremely skilful in, energetic at, or devoted to a given activity, esp a sport

      a demon at cycling

   2. ( as modifier )

      a demon cyclist

5. a variant spelling of daemon

6. informal 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

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Usage

What does demon- mean? Demon- is a combining form used like a prefix meaning “demon.” It is used in a few technical terms, especially in theology. Demon- comes from the Greek daimónion, meaning “thing of divine nature” and ultimate source of the English word demon. Among Jewish and Christian writers, daimónion was used to mean “evil spirit.”Demon- is a variant of demono-, which loses its -o- when combined with words or word elements beginning with vowels. Want to know more? Read our Words That Use demono- article.

Etymology

Origin of demon

1350–1400; Middle English < Latin daemonium < Greek daimónion, thing of divine nature (in Jewish and Christian writers, evil spirit), neuter of daimónios, derivative of daímōn; demon ( def. 6 ) < Latin; daemon

Explanation

A demon is an evil, mythical monster or spirit. Stories about demons are featured in a variety of different religious traditions. You might come across a demon in a supernatural fairy tale, or even in the Christian Bible. Demons are often interchangeable with devils, and both words are sometimes used to talk about a cruel, fiendish person. If you're extremely good at something, you also might be described as a demon: "She's a demon at bowling." The Greek root, daimon, doesn't have the same negative connotations — it means "spirit or deity."

Example Sentences

Getting back home, though, I’ll need to face the demon again.

From The Wall Street Journal • Apr. 12, 2026

I’ll note that the demon is a more honest and fair negotiator than his vassals, who occasionally cheat and are punished in exactly the way you’re hoping to see.

From Los Angeles Times • Mar. 19, 2026

The original film follows main characters Rumi, Mira and Zoey from the K-pop group Huntr/x as they grapple with fame and their secret lives as demon hunters.

From BBC • Mar. 12, 2026

Now, the Duffer Brothers are at last showing what happened to Will while he was trapped in the Upside Down, the phantasmic shadow realm ruled by a man-made demon lord.

From Salon • Nov. 24, 2025

Aru imagined it saying, Throw me at a demon!

From "Aru Shah and the End of Time" by Roshani Chokshi

Related Words

• fiend
• malignant spirit
• monster
• vampire
• villain