diabolical

adjective

di·​a·​bol·​i·​cal ˌdī-ə-ˈbä-li-kəl 

variants or diabolic

ˌdī-ə-ˈbä-lik 

: of, relating to, or characteristic of the devil : extremely evil

a diabolical plot

diabolically

ˌdī-ə-ˈbä-li-k(ə-)lē 

adverb

diabolicalness

ˌdī-ə-ˈbä-li-kəl-nəs 

noun

Did you know?

Like the word devil, "diabolical" traces back to Latin diabolus, which itself descends from Greek diabolos, a word that literally means "slanderer." In English, "diabolical" has many nuances of meaning. It can describe the devil himself (as in "my diabolical visitor") or anything related to or characteristic of him in appearance, behavior, or thought; examples include "diabolical lore," "a diabolical grin," and "a diabolical plot." In British slang, "diabolical" can also mean "disgraceful" or "bad," as in "the food was diabolical."

Synonyms of diabolical

• demonic
• sinister
• malicious

Examples of diabolical in a Sentence

the police quickly mobilized to track down the diabolical criminals before they struck again

Recent Examples on the Web

Violet McGraw, known for playing the titular role in the M3GAN franchise, is set to lead a YA comedy feature in which her character is similarly protective of those close to her but in a slightly less diabolical way. —Ryan Gajewski, HollywoodReporter, 15 Jan. 2026

But the harder the novice looks — and the greater the chaos inside them longing for order, even of a diabolical nature — the more clearly the horror will appear. —Sara Holdren, Vulture, 9 Jan. 2026

The federal government right now is diabolical. —Mara H. Gottfried, Twin Cities, 9 Jan. 2026

That, to me, was the simplest and the most diabolical part of the story. —Greta Cross, USA Today, 30 Dec. 2025

Word History

Etymology

diabolical from diabolic + -ical; diabolic going back to Middle English deabolik, borrowed from Middle French & Late Latin; Middle French dyabolique, borrowed from Late Latin diabolicus, borrowed from Late Greek diabolikós, going back to Greek, "slanderous," from diábolos "accuser, backbiter, slanderer" + -ikos -ic entry 1 — more at devil entry 1

First Known Use

15th century, in the meaning defined above

Rhymes for diabolical

• follicle
• symbolical

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Kids Definition

diabolical

adjective

di·​a·​bol·​i·​cal ˌdī-ə-ˈbäl-i-kəl 

variants or diabolic

-ˈbäl-ik 

: of, relating to, or characteristic of the devil : fiendish

diabolically

-i-k(ə-)lē 

adverb

diabolicalness

-i-kəl-nəs 

noun