Synonyms of fiendish in English:


See US English definition of fiendish

See UK English definition of fiendish

See Spanish definition of diabólico


1‘a fiendish torturer’

wicked, cruel, vicious, evil, nefarious, unspeakable
brutal, brutish, savage, barbaric, barbarous, beastly, inhuman, murderous, bloodthirsty, ferocious
ruthless, heartless, pitiless, merciless, black-hearted, unfeeling
malevolent, malicious, villainous, malignant, devilish, diabolical, hellish, demonic, satanic, Mephistophelian, ungodly
odious, base
archaic, humorous dastardly

2‘a fiendish plot’

cunning, clever, ingenious, artful, crafty, canny, wily, guileful, devious, scheming, shrewd, astute, sharp, sharp-witted, imaginative
informal foxy, savvy, sneaky, cute
Scottish, Northern English informal pawky
South African informal slim
rare vulpine, carny

3‘a fiendish puzzle’

difficult, complex, complicated, intricate, involved, knotty, thorny, ticklish, abstruse, impenetrable, unfathomable
challenging, puzzling, baffling, perplexing, bemusing