Extremely evil or cruel; expressive of cruelty or befitting hell:
— Something demonic in him--something that could be cruel.

synonyms: diabolic, diabolical, fiendish, hellish, infernal, satanic, unholy.

Roget 980: demonic, demonical, impish, demoniacal; fiendish, fiend-like; supernatural, weird, uncanny, unearthly, spectral; ghostly, ghost-like; elfin, elvin^†, elfish, elflike^†; haunted; pokerish [U.S.].    possessed, possessed by a devil, possessed by a demon.    ... show more

Polish: demoniczny, szatański, sataniczny