English Reference
noun

demon

n.
US /ˈdimən/ UK /dˈiːmən/ de·mon UK spelling demon's, demon's

  1. 01 B2 Upper Intermediate Religion

    an evil spirit or supernatural being in stories and religion.

    an evil supernatural being or spirit, typically associated with hell or malevolence.

    Simple

    In the old story, a brave knight fights a demon to save the village.

    In context

    The cathedral's architecture featured stone gargoyles intended to represent the demons that the faithful were taught to fear.

  2. 02 B2 Upper Intermediate

    a strong, painful feeling or a bad habit that is hard to control.

    a source of persistent psychological torment, distress, or a destructive personal habit.

    Simple

    The retired athlete struggled with his own demons after his career ended.

    In context

    The biography explores how the artist battled his inner demons through his work, often painting late into the night to escape his anxiety.

  3. 03 C1 Advanced Informal

    someone who does something with a lot of energy, speed, or skill.

    a person who performs a particular activity with great enthusiasm, energy, or technical proficiency.

    Simple

    She is a demon on the tennis court and rarely loses a match.

    In context

    Known as a demon for detail, the editor spent weeks ensuring every citation in the manuscript was perfectly formatted.

  4. 04 C1 Advanced Technical Computing

    a background program on a computer that handles specific tasks without the user seeing it.

    a background process that handles system tasks or requests without direct user intervention; often spelled 'daemon'.

    Simple

    The print demon handles all the documents you send to the printer.

    In context

    The system administrator noticed that a rogue demon was consuming excessive CPU cycles, slowing down the entire server network.

  5. 05 C2 Proficiency Technical Science

    an imaginary creature used in science to explain how energy and heat work.

    a hypothetical being used in thought experiments to illustrate physical laws, most notably Maxwell's demon.

    Simple

    Maxwell's demon is a famous idea used to talk about the laws of physics.

    In context

    The professor used the concept of Maxwell's demon to challenge the students' understanding of the second law of thermodynamics.

It’s a folk-horror spoof about an up-himself critic obliged by demons to learn the error of his ways.

The Guardian· 14 Aug 2026

Toño’s quest to write the book involves sleuthing, research, interviews, a journey along Peru’s Pacific coast to Molfino’s birthplace, and battles with his own demons – in particular, a phobia about rats.

The Guardian· 11 Aug 2026
This entry
Level C1 · Advanced
Frequency Common
Updated