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Synonyms

fiendish

American  
[feen-dish] / ˈfin dɪʃ /

adjective

  1. diabolically cruel and wicked.


fiendish British  
/ ˈfiːndɪʃ /

adjective

  1. of or like a fiend

  2. diabolically wicked or cruel

  3. informal extremely difficult or unpleasant

    a fiendish problem

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • fiendishly adverb
  • fiendishness noun

Etymology

Origin of fiendish

First recorded in 1520–30; fiend + -ish 1

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

To make up for it, he pulled out a completely different jumping pass on the fly, starting with a different quad—-and then landed another fiendish combination.

From The Wall Street Journal • Feb. 9, 2026

That is good news for Inter who have a fiendish run of fixtures to close their league phase campaign, including clashes at the San Siro with Liverpool and Premier League leaders Arsenal.

From Barron's • Nov. 5, 2025

From the celebration of the deceased known as Día de los Muertos, to the foreboding thrills and life lessons underpinning Latin America’s fiendish folklore, spooky things are as revered as they are feared.

From Los Angeles Times • Oct. 30, 2025

The Sidemen act as hosts and executive producers, putting their inmates through fiendish challenges that can see the £1m prize pot reduced.

From BBC • Jun. 3, 2024

Then, as the four badly shaken Egyptians turned loose of each other and tried to regain their dignity, the monster and the box-man leaned on each other and choked with fiendish laughter.

From "The Egypt Game" by Zilpha Keatley Snyder