adjective
having or manifesting qualities associated with devils, demons, and fiends
inflicted fiendish tortures on his captive
Synonyms: demoniac, demonian, demonic, devilish, diabolic, diabolonian, satanic, serpentine, unhallowed
Related Word: hellish, infernal; baleful, malefic, maleficent, malign, sinister; malevolent, malicious, malignant; atrocious, heinous, monstrous, outrageous; barbarous, cruel, ferocious, inhuman, savage, vicious
Contrasted words: benign, benignant, kind, kindly; gentle, mild; compassionate, sympathetic, tender