adjective
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excruciatingly bad; outrageous
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(intensifier)
a diabolical liberty
Other Word Forms
Etymology
Origin of diabolical
First recorded in 1500–10; from Late Latin diabolicus ( see diabolic ( def. )) + -al 1 ( def. )
Explanation
Diabolical means "evil." This is a strong word. Too much math homework might seem unfair, but it probably isn't diabolical. Diabolical is related to the Spanish word diablo, which means "devil." In many religions and mythologies, you can't get any more evil than a devil, so diabolical is a powerful term, stronger than even despicable, which is another strong word for things that are hateful. Diabolical things are also intentional. If you got hit by lightning, that's awful and harmful, but it's not diabolical. If someone deliberately runs you over with a car, that's much more diabolical.
Vocabulary lists containing diabolical
Persepolis
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100 SAT Words Beginning with "D"
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Similes from Top AP English Exam Novels
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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.
Product designers are coming up with novel ways to rouse deep sleepers that border on diabolical, including clocks that deliver 300-volt electric shocks and donate snoozers’ money to charity.
From The Wall Street Journal • Mar. 6, 2026
"It's a diabolical situation that consumers find themselves in and especially at a really important time of year for families and for businesses," Mr Walker said.
From BBC • Nov. 15, 2025
The promise remains dazzling and deliciously diabolical enough for adherents to forget that deals with the devil always come with a hidden, inescapable price tag.
From Salon • Nov. 1, 2025
It’s less stupid, for starters, and more diabolical.
From Slate • Jul. 22, 2025
It gave me almost a turn to see again one of the letters which I had seen on the Count’s table before I knew of his diabolical plans.
From "Dracula" by Bram Stoker
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
