DIABOLIC

adj. 1 diabolical, devilish, satanic, Mephistophelian, demonic, demoniac(al), fiendish, hellish, infernal His interest in the supernatural included participation in diabolic rituals of the most repulsive kind 2 diabolical, cruel, wicked, iniquitous, evil, fiendish, appalling, dreadful, inhuman, atrocious, execrable, abominable, awful, terrible, damnable, accursed, horrid, horrible, hideous, monstrous, odious, vile, base, corrupt, foul, depraved, flagitious, heinous, malicious, malevolent, malign, maleficent, sinister, sinful, impious, bad The prisoners suffered the most diabolic treatment