fiendish

F4I1E1N1D2I1S1H4
/ˈfiːndɪʃ/

adjective

Sinister; evil; like a fiend.

“a fiendish crossword puzzle”

Similar
connivingdemonicdiabolicdiabolicalhellishinfernalsatanicunholy
UncommonScrabble 15
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Meanings

adjectivefiendish (comparative more fiendish, superlative most fiendish)

comparative more fiendish · superlative most fiendish

  1. Sinister; evil; like a fiend.

    She had a fiendish smile that hinted at a cunning plan.

    1 more example

    The detective was puzzled by the fiendish plot to steal the diamonds.

    Synonyms: conniving

  2. Very difficult.

    a fiendish crossword puzzle

    1 more example

    The exam was filled with fiendish questions that made no sense.

Synonyms & antonyms

adjectiveSinister; evil; like a fiend.

Similar
conniving

More synonyms by meaning

adjectiveextremely evil or cruel; expressive of cruelty or befitting hell

Similar
demonicdiabolicdiabolicalhellishinfernalsatanicunholyevil
Also see
demonicdevilishdiabolicdiabolicalfiendlikehellishinfernalsatanicunholy

Synonym sets from Open English WordNet, CC BY 4.0.

Origin

From fiend + -ish.

Full word history & related roots →

Translations

Bulgarian зъл, демоничен
  • зъл (zăl)sinister, evil
  • демоничен (demoničen)sinister, evil
Chinese 惡魔似 /恶魔似, 恶魔似
  • 惡魔似 /恶魔似sinister, evil
  • 恶魔似sinister, evil
Dutch duivels, sinister
  • duivelssinister, evil
  • sinistersinister, evil
Esperanto diabla
  • diablasinister, evil
Finnish pirullinen, paholaismainen
  • pirullinensinister, evil
  • paholaismainensinister, evil
French diabolique
  • diaboliquesinister, evil
German teuflisch
  • teuflischsinister, evil
Greek μοχθηρός
  • μοχθηρός (mochthirós)sinister, evil
Hindi भुतहा
  • भुतहा (bhuthā)sinister, evil
Hungarian ördögi, pokoli
  • ördögisinister, evil
  • pokolisinister, evil
  • ördöngössinister, evil
Italian diabolico, demoniaco
  • diabolicosinister, evil
  • demoniacosinister, evil
Korean 악마
  • 악마 (angma)sinister, evil
Norwegian djevelsk
  • djevelsksinister, evil
Polish diabelski, szatański
  • diabelskisinister, evil
  • szatańskisinister, evil
Portuguese sinistro, diabólico
  • sinistrosinister, evil
  • diabólicosinister, evil
Romanian sinistru, rău
  • sinistrusinister, evil
  • răusinister, evil
  • demonicsinister, evil
Russian дья́вольский
  • дья́вольский (dʹjávolʹskij)sinister, evil
Spanish diabólico
  • diabólicosinister, evil

Rhymes & wordplay

Anagrams

finished
Cite this entry
APA

fiendish. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/fiendish

MLA

“fiendish.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/fiendish. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “fiendish,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/fiendish.

Source: fiendish on Wiktionary, CC BY-SA 4.0.