fiendish

• POS: Adjective
• HYPHEN: fiend=ish

CIDE DICTIONARY

fiendish, a. 

 Like a fiend; diabolically wicked or cruel; infernal; malignant; devilish; hellish.  [1913 Webster]

THESAURUS

fiendish

Draconian, Mephistophelian, Tartarean, animal, anthropophagous, atrocious, bad, baleful, barbaric, barbarous, beastly, bestial, bloodthirsty, bloody, bloody-minded, brutal, brutalized, brute, brutish, cannibalistic, cruel, cruel-hearted, cursed, damnable, demoniac, demoniacal, demonic, demonish, demonlike, devil-like, devilish, diabolic, diabolical, evil, execrable, fell, feral, ferocious, fiendlike, fierce, ghoulish, heinous, hellborn, hellish, infernal, inhuman, inhumane, malefic, maleficent, malevolent, malicious, malign, malignant, monstrous, murderous, ogreish, outrageous, ruthless, sadistic, sanguinary, sanguineous, satanic, savage, serpentine, sharkish, sinister, slavering, subhuman, truculent, unchristian, uncivilized, ungodly, unhallowed, unhuman, vicious, wicked, wolfish

ROGET THESAURUS

fiendish

Demon

N demon, daemon, demonry, demonology, evil genius, fiend, familiar, daeva, devil, bad spirit, unclean spirit, cacodemon, incubus, Eblis, shaitan, succubus, succuba, Frankenstein's monster, Titan, Shedim, Mephistopheles, Asmodeus, Moloch, Belial, Ahriman, fury, harpy, Friar Rush, vampire, ghoul, afreet, barghest, Loki, ogre, ogress, gnome, gin, jinn, imp, deev, lamia, bogie, bogeyman, bogle, nis, kobold, flibbertigibbet, fairy, brownie, pixy, elf, dwarf, urchin, Puck, Robin Goodfellow, leprechaun, Cluricaune, troll, dwerger, sprite, ouphe, bad fairy, nix, nixie, pigwidgeon, will-o'-the wisp, ghost, revenant, specter, apparition, spirit, shade, shadow, vision, hobglobin, goblin, orc, wraith, spook, boggart, banshee, loup-garou, lemures, evil eye, merman, mermaid, merfolk, siren, satyr, faun, manito, manitou, manitu, possession, demonic possession, diabolic possession, insanity, Maxwell's demon, demoniac, demonic, demonical, impish, demoniacal, fiendish, fiend-like, supernatural, weird, uncanny, unearthly, spectral, ghostly, ghost-like, elfin, elvin, elfish, elflike, haunted, pokerish, possessed, possessed by a devil, possessed by a demon, demonically.

Malevolence

N malevolence, bad intent, bad intention, unkindness, diskindness, ill nature, ill will, ill blood, bad blood, enmity, hate, malignity, malice, malice prepense, maliciousness, spite, despite, resentment, uncharitableness, incompassionateness, gall, venom, rancor, rankling, virulence, mordacity, acerbity churlishness, hardness of heart, heart of stone, obduracy, cruelty, cruelness, brutality, savagery, ferity, ferocity, barbarity, inhumanity, immanity, truculence, ruffianism, evil eye, cloven foot, torture, vivisection, ill turn, bad turn, affront, outrage, atrocity, ill usage, intolerance, persecution, tender mercies, unkindest cut of all, 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, surly, sullen, cold, cold-blooded, cold-hearted, black-hearted, hard-hearted, flint-hearted, marble-hearted, stony-hearted, hard of heart, unnatural, ruthless, relentless, cruel, brutal, brutish, savage, savage as a bear, savage as a tiger, ferine, ferocious, inhuman, barbarous, barbaric, semibarbaric, fell, untamed, tameless, truculent, incendiary, bloodthirsty, atrocious, bloodyminded, fiendish, fiendlike, demoniacal, diabolic, diabolical, devilish, infernal, hellish, Satanic, Tartaran, malevolently, with bad intent, cruel as death, hard unkindness' alter'd eye, homo homini lupus, mala mens, malus animus, rich gifts wax poor when givers prove unkind, sharp-tooth'd unkindness.

Vice

N vice, evil-doing, evil courses, wrongdoing, wickedness, viciousness, iniquity, peccability, demerit, sin, Adam, old Adam, offending Adam, immorality, impropriety, indecorum, scandal, laxity, looseness of morals, enphagy, dophagy, exophagy, want of principle, want of ballast, obliquity, backsliding, infamy, demoralization, pravity, depravity, pollution, hardness of heart, brutality, corruption, knavery, profligacy, flagrancy, atrocity, cannibalism, lesbianism, Sadism, infirmity, weakness, weakness of the flesh, frailty, imperfection, error, weak side, foible, failing, failure, crying sin, besetting sin, defect, deficiency, cloven foot, lowest dregs of vice, sink of iniquity, Alsatian den, gusto picaresco, fault, crime, criminality, sinner, brothel, gambling house, joint, opium den, shooting gallery, crack house, vicious, sinful, sinning, wicked, iniquitous, immoral, unrighteous, wrong, criminal, naughty, incorrect, unduteous, undutiful, unprincipled, lawless, disorderly, contra bonos mores, indecorous, unseemly, improper, dissolute, profligate, scampish, unworthy, worthless, desertless, disgraceful, recreant, reprehensible, blameworthy, uncommendable, discreditable, disreputable, Sadistic, base, sinister, scurvy, foul, gross, vile, black, grave, facinorous, felonious, nefarious, shameful, scandalous, infamous, villainous, of a deep dye, heinous, flagrant, flagitious, atrocious, incarnate, accursed, Mephistophelian, satanic, diabolic, hellish, infernal, stygian, fiendlike, hell-born, demoniacal, devilish, fiendish, miscreated, misbegotten, demoralized, corrupt, depraved, evil-minded, evil-disposed, ill-conditioned, malevolent, heartless, graceless, shameless, virtueless, abandoned, lost to virtue, unconscionable, sunk in iniquity, lost in iniquity, steeped in iniquity, incorrigible, irreclaimable, obdurate, reprobate, past praying for, culpable, reprehensible, unjustifiable, indefensible, inexcusable, inexpiable, unpardonable, irremissible, weak, frail, lax, infirm, imperfect, indiscrete, demoralizing, degrading, wrong, sinfully, without excuse, Int, O tempora!, O mores!, alitur vitium vivitque tegendo, genus est mortis male vivere, mala mens malus animus, nemo repente fuit turpissimus, the trail of the serpent is over them all, to sanction vice and hunt decorum down.