Showing the cunning or ingenuity or wickedness typical of a devil:
— The diabolical expression on his face.

synonyms: devilish, diabolic, mephistophelean, mephistophelian.

Polish: czarci

Extremely evil or cruel; expressive of cruelty or befitting hell:
— Diabolical sorcerers under the influence of devils.

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

Roget 907: malevolent, unbenevolent; unbenign; ill-disposed, ill-intentioned, ill-natured, ill-conditioned, ill-contrived; evil-minded, evil-disposed; black-browed^†.    malicious; malign, malignant; rancorous; despiteful, spiteful; mordacious, caustic, bitter, envenomed, acrimonious, virulent; unamiable, uncharitable; maleficent, venomous, grinding, galling.    harsh, disobliging; unkind, unfriendly, ungracious; inofficious^†; invidious; uncandid; churlish etc. (discourteous) 895; surly, sullen etc. 901.1. cold, cold-blooded, cold-hearted; black-hearted, hard-hearted, flint-hearted, marble-hearted, stony-hearted; hard of heart, unnatural; ruthless etc. (unmerciful) 914.1; relentless etc. (revengeful) 919.    cruel; brutal, brutish; savage, savage as a bear, savage as a tiger; ferine^†, ferocious; inhuman; barbarous, barbaric, semibarbaric, fell, untamed, tameless, truculent, incendiary; bloodthirsty etc. (murderous) 361; atrocious; bloodyminded^†.    fiendish, fiendlike^†; demoniacal; diabolic, diabolical; devilish, infernal, hellish, Satanic; Tartaran.    ... show more

Polish: demoniczny, szatański, sataniczny