Definition of "demoniac"

demoniac

/dɪˈməʊnɪak/

adjective
comparative more demoniac, superlative most demoniac
1. Possessed or controlled by a demon.
2. Of or pertaining to demons; demonic.
  Quotations
  How dark may be the hiding of God's face,Or what demoniac forms may seize the helmOf reason...
  1827, Lydia Huntley Sigourney, Poems, 1827: The Sweetness of Life, page 24
  Animal fury and orgiastic licence here whipped themselves to demoniac heights by howls and squawking ecstasies that tore and reverberated through those nighted woods like pestilential tempests from the gulfs of hell.
  1928 February, H[oward] P[hillips] Lovecraft, “The Call of Cthulhu”, in Farnsworth Wright, editor, Weird Tales: A Magazine of the Bizarre and Unusual, volume 11, number 2, Indianapolis, Ind.: Popular Fiction Pub. Co., pages 159–178 and 287
  There was movement everywhere, screaming, demoniac activity; the old man was coming across the tumbling logs.
  1955, William Golding, The Inheritors, Faber & Faber, published 2005, page 216
noun
plural demoniacs
1. Someone who is possessed by a demon.
  Quotations
  The exorcism was dropped from the second Edwardian Prayer Book, because of its implication that unbaptised infants were demoniacs […].
  1971, Keith Thomas, Religion and the Decline of Magic, Folio Society, published 2012, page 53