FIENDISH Synonyms: 107 Similar and Opposite Words

fiendish

adjective

ˈfēn-dish

Definition of fiendish

as in demonic

of, relating to, or worthy of an evil spirit a fiendish delight in playing cruel tricks

Synonyms & Similar Words

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Antonyms & Near Antonyms

as in brutal

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

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Antonyms & Near Antonyms

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of fiendish Plotting kind of my most fiendish, happy, mad scientist state. — Literary Hub, 4 May 2026 The soloist in the Sibelius was a mediocre violinist ill-equipped to deal with the concerto’s profound emotions and fiendish technical demands. — Luis Palomares, Miami Herald, 27 Feb. 2026 Jim Carrey plays the eponymous Grinch, a fiendish Whoville outlaw who declares war on the festive season. — Danny Horn, Entertainment Weekly, 29 Nov. 2025 Miller works with him to refine the routes, placing checkpoints that are both fair and fiendish. — New Atlas, 1 Nov. 2025 See All Example Sentences for fiendish

Recent Examples of Synonyms for fiendish

Adjective

The devil invades a Georgetown home, and holy men have quite the job to do on a demonic little girl.

— Brian Truitt, USA Today, 1 July 2026
Carlson has spoken of his own brush with demonic forces, who left him bloodied and scratched in the night, while his wife and their four spaniels slept undisturbed.

— Eliza Griswold, New Yorker, 22 June 2026

Definition of demonic

Adjective

And such attacks are not merely tactics of war, but the brutal intersection of the logic of war and the logic of climate vulnerability.

— Sarah Yerkes, Time, 10 July 2026
That film culminated in the brutal defeat of House Atreides by rival House Harkonnen, with Paul and his mother, Lady Jessica (Rebecca Ferguson), fleeing to the desert and taking refuge among the Fremen.

— Jennifer Ouellette, ArsTechnica, 9 July 2026

Definition of brutal

Adjective

Dorothea centers on a Sacramento woman (Davis) who ran a boarding house for the less fortunate in the 1980s, but her seemingly benevolent actions belied her sinister motives.

— Nellie Andreeva, Deadline, 7 July 2026
The score drips with a sinister ostinato as the rats scurry into every corner of her castle.

— Amanda Whiting, Vulture, 6 July 2026

Definition of sinister

Adjective

The heat has become so unbearable in Japan that weather officials in April announced a new term for days when maximum temperatures exceed 104 degrees — kokushobi, meaning harsh or cruel heat, according to the Japan Times.

— Los Angeles Times, Los Angeles Times, 6 July 2026
For thousands of Venezuelans, however, the lack of definitive answers has become one of the tragedy’s cruelest consequences.

— Antonio María Delgado, Miami Herald, 3 July 2026

Definition of cruel

Adjective

When Ahab first speaks to the crew about Moby Dick, his diabolical charisma soon infects the men who, apart from Starbuck, enthusiastically join him in his monomaniacal crusade.

— Literary Hub, Literary Hub, 6 July 2026
From perhaps the most diabolical spot on the entire course.

— Brendan Quinn, New York Times, 20 June 2026

Definition of diabolical

Adjective

The early Cold War liberals had read their history books and seen how the French Revolution had begun with high progressive hopes but descended into a vicious bloodbath.

— David Brooks, The Atlantic, 8 July 2026
After a similarly vicious storm struck the New York area late Friday, hundreds of thousands of utility customers were left without power, trains to New Jersey were canceled and thousands of trees were damaged or uprooted.

— Los Angeles Times, Los Angeles Times, 4 July 2026

Definition of vicious

Adjective

Anthropic has reported banning accounts and tightening filters after detecting attempts to use Claude for phishing emails, malicious code and safeguard bypasses.

— Ron Schmelzer, Forbes.com, 10 July 2026
Rather than needing years of specialist knowledge, attackers can now use large language models to perform reconnaissance, identify weaknesses, write malicious code and map computer networks in ways that previously demanded significant expertise.

— Christopher McFadden, Interesting Engineering, 10 July 2026

Definition of malicious

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fiendish

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“Fiendish.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/fiendish. Accessed 14 Jul. 2026.

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Synonyms of fiendish

adjective

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