[dih-moh-nee-ak, dee-muh-nahy-ak]

adjective Also de·mo·ni·a·cal [dee-muh-nahy-uh-kuhl] /ˌdi məˈnaɪ ə kəl/.

of, relating to, or like a demon; demonic: demoniac laughter.
possessed by or as by an evil spirit; raging; frantic.


a person seemingly possessed by a demon or evil spirit.

Origin of demoniac

1350–1400; Middle English < Late Latin daemoniacus < Greek daimoniakós, equivalent to daimóni(os) pertaining to a daemon + -akos -ac
Related formsde·mo·ni·a·cal·ly [dee-muh-nahy-ik-lee] /ˌdi məˈnaɪ ɪk li/, adverb

Antonyms for demoniac Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for demoniac

Historical Examples of demoniac

  • It was with the greatest difficulty that I was delivered from the clutches of this demoniac.

    My Double Life

    Sarah Bernhardt

  • Martha Brossier, daughter of a weaver at Romorantin, was shown as a demoniac, in 1578.

    The Phantom World

    Augustin Calmet

  • But the path of these demoniac men was marked by the ravages of fiends.

  • It looked a demoniac place, a smoke-wreathed platform in some Inferno circle.

    The Long Roll

    Mary Johnston

  • A great, black, cylindrical shell came with a demoniac shriek.

    The Long Roll

    Mary Johnston

British Dictionary definitions for demoniac


adjective also: demoniacal (ˌdiːməˈnaɪəkəl)

of, like, or suggestive of a demon; demonic
suggesting inner possession or inspirationthe demoniac fire of genius
frantic; frenzied; feverishdemoniac activity


a person possessed by an evil spirit or demon
Derived Formsdemoniacally, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for demoniac

c.1400, "possessed, insane," earlier (late 14c.) as a noun, "one who is possessed," from Late Latin daemoniacus (c.200), from Greek daimoniakos "possessed by a demon," from diamon (see demon).

Online Etymology Dictionary, © 2010 Douglas Harper