Synonyms of fiendish

1 Syllable

cruel

2 Syllables

brutish, ghoulish, evil, theurgic, monstrous, undead, tranced, vicious, impish, chthonian, feller, grody, hellborn, naughtiest, wicked, pixieish, beastly, hellish, runic, witching, naughtier, naughty

3 Syllables

wizardly, inhuman, diabolic, magical, infernal, malicious, teratoid, theurgical, demoniac, demonic, sadistic, savage, coldblooded, atrocious, devilish, possessed, unearthly, satanic, sulphurous, nefarious, miscreated, obsessed, sorcerous, witchlike

4 Syllables

diabolical, demonical, ensorcelled, necromantic, talismanic, demoniacal, inhumane, thaumaturgic

5 Syllables

hyperphysical, spiritualistic, telekinetic, mephistophelian, thaumaturgical

7 Syllables

parapsychological