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

These diabolical onslaughts are further weaponized by the reckless defunding of scientific and medical research and the undermining of public libraries (including the Library of Congress), museums, and other cultural institutions. —Donna Seaman june 18, Literary Hub, 18 June 2025

Play diabolical games, face off against the Front Man, and betray your friends for a chance to win it all. —Jennifer Maas, Variety, 17 June 2025

Rice owns that record now with a diabolical 197 receiving touchdowns. —Jim Reineking, USA Today, 17 June 2025

Promising an apocalypse by the ayatollahs who were getting ever closer to obtaining a nuclear weapon to carry out that diabolical wish, Israel had every right to hit Iran to disable its uranium enrichment facilities and its ballistic missile infrastructure. —New York Daily News Editorial Board, New York Daily News, 14 June 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