Dictionary.com
Thesaurus.com
Synonyms

diabolical

American  
[dahy-uh-bol-i-kuhl] / ˌdaɪ əˈbɒl ɪ kəl /
Also diabolic

adjective

  1. having the qualities of a devil; devilish; fiendish; outrageously wicked.

    a diabolical plot.

  2. pertaining to or actuated by a devil.


diabolical British  
/ ˌdaɪəˈbɒlɪkəl /

adjective

  1. excruciatingly bad; outrageous

  2. (intensifier)

    a diabolical liberty

"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

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.

Keep Reading on Vocabulary.com

Vocabulary lists containing diabolical

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.

See Examples For:

The Los Angeles Times described Mold-A-Ramas as “a diabolical cross between a jukebox and a pinball machine” that cost $3,600 apiece, or about $39,500 today.

From Los Angeles Times Aug. 10, 2026

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

Later, John and Paul attempt diabolical accents while relating the story of Count Balder and Felpin Mansions, “the eccentric son of Baron Landsberg, the inventor of the rack,” including a variety of sound effects.

From Salon Dec. 23, 2025

It’s less stupid, for starters, and more diabolical.

From Slate Jul. 22, 2025

There was a sinister and unlikely coincidence exposed that was too diabolical in implication to be anything less than the most hideous of omens.

From "Catch-22" by Joseph Heller

Vocabulary.com logo
by dictionary.com

Dictionary.com's Learning Companion

Go beyond just looking up words.
Remember them forever with VocabTrainer.

Start training