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 : devilish

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

• demonic
• demonical
• sinister
• evil
• 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

Also, after saving the school from Tyler (Hunter Doohan), who was a secret Hyde controlled by the diabolical Marilyn Thornhill (Christina Ricci), Wednesday has become a celebrity of sorts on campus. —Aramide Tinubu, Variety, 6 Aug. 2025

In his diabolical new thriller, Park Chan-wook (Decision to Leave, NYFF60) crafts a dark fable about the cutthroat nature of contemporary work culture and the domestic desperation for material comfort. —Jill Goldsmith, Deadline, 5 Aug. 2025

The show somehow complicates things even further in its equally diabolical second season. —Tanya Melendez, EW.com, 1 Aug. 2025

That diabolical racket was antisocial but also antiwar. —Craig Jenkins, Vulture, 25 July 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