fiendish

1 of, relating to, or worthy of an evil spirit a fiendish delight in playing cruel tricks Synonyms cacodemonic, demoniac (also demoniacal), demonian, demonic (also demonical), devilish, diabolical (or diabolic), Luciferian, satanic Related Words hellish, infernal; baleful, evil, sinister; malevolent, malicious, malignant; heinous, monstrous; black, immoral, iniquitous, nefarious, vicious, vile, villainous, wicked; barbarous, cruel, ferocious, inhuman, savage Near Antonyms celestial, heavenly; beneficent, benevolent, benign, benignant; godly, holy, sainted, saintly; ethical, good, moral, righteous, virtuous Antonyms angelic (or angelical)

2 having or showing the desire to inflict severe pain and suffering on others shook with fiendish laughter as he watched his victims writhe in agony Synonyms atrocious, barbaric, barbarous, brutal, brute, butcherly, cruel, heartless, inhuman, inhumane, sadistic, savage, truculent, vicious, wantonRelated Words hard-hearted, ironhearted, merciless, pitiless, ruthless, stonyhearted, unfeeling; fell, ferocious, grim; bloodthirsty, cutthroat, murderous, sanguinary, sanguine; catty, despiteful, hateful, malevolent, malicious, malign, malignant, mean, nasty, spiteful, vindictive; draconian, draconic, hardhanded, harsh, heavy-handed, oppressiveNear Antonyms tender, warm, warmhearted; charitable, clement, lenient, merciful, pitying; pacific, peaceable, peacefulAntonyms benign, benignant, compassionate, good-hearted, humane, kind, kindhearted, sympathetic, tenderhearted