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.
That’s when UConn coach Dan Hurley dialed up “Twelve On,” a diabolical full-court trap that would make or break his entire season.
From The Wall Street Journal • Mar. 30, 2026
"In the midst of the fear of my grandmother's health and well-being this was diabolical, this was shambolic, that the first person to contact me was describing this as a 'wee incident'."
From BBC • Dec. 18, 2025
The diabolical move from Riley would pay off.
From Los Angeles Times • Nov. 8, 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
Lord Dunmore’s letters to General Howe, which very fortunately fell into my hands, and were enclosed by me to Congress, will let you pretty fully into his diabolical schemes.
From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume II: The Kingdom on the Waves" by M.T. Anderson
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.
