diabolical
Diabolical means evil or extremely bad, but online it is often a grinning reaction to a clever prank or an outrageous move. What it is aimed at tells you which.
By Cal Hewitt, Gen X · ·
What it means
Diabolical is a negative word at its core. Cambridge Dictionary defines it as "extremely bad or shocking" and as "evil, or caused by the Devil", and Oxford Learner's Dictionaries gives "morally bad and evil; like a devil". In news about crime, cruelty or a villain, that is exactly what the speaker means, and nobody is joking. British English adds a plain complaint with no devil in it. Oxford marks a British informal sense, "extremely bad or annoying", and Dictionary.com lists a British informal sense too. "The traffic was diabolical" or "their customer service is diabolical" just means awful. Wiktionary also records two slang senses, "cunning or devious" and "crazy or wild", which is where the online use lives. Online, the word is often deliberately oversized. A comment calling a prank, a snack combination or a gaming move diabolical is usually half scolding and half applause, and calling a minor inconvenience diabolical is the joke. One TikTok from @biggestswave, posted September 28, 2026 and at 49,701 views when checked, is captioned "You my mans but that sentence diabolical" with a long string of laughing emojis, a typical joking use. The same word with no emoji under a report about someone being hurt is condemnation. Laughing emojis, the object of the word and the relationship between speaker and target settle which one you are reading. Diabolical is not a swear word or a slur, and anyone can say it. It becomes rude when aimed at a person as a serious accusation of cruelty. In an email or a report, use it only when "extremely bad" or "morally wicked" is what you mean, since a reader may not know whether you are joking.
See the quick definition in the diabolical dictionary entry.
How to use it
“he put pineapple on the burger and called it a salad. that's diabolical”
Playful, mock outrage at a food combination.
“you hid the remote for a whole week?? you're diabolical”
Teasing a friend after a harmless prank, half scolding and half admiring.
“the traffic on the m6 was diabolical”
British complaint. It just means terrible.
“police called the scheme a diabolical plot to defraud elderly residents”
Serious news use. It means genuinely wicked.
Where it came from
The Online Etymology Dictionary dates the adjective diabolical to around 1500, with the sense "befitting the devil" from the 1540s. It is built from diabolic plus -al. Diabolic is recorded from the late 14th century, from Old French diabolique and Late Latin diabolicus, from Ecclesiastical Greek diabolikos, "devilish", which comes from diabolos, the Devil. No single coiner is documented.
The British informal sense of "extremely bad" came later, and the online use builds on both the devilish sense and that British intensifier. No first date or creator is documented for the playful online sense; it circulates across TikTok, Instagram, Reddit, gaming chats and meme communities.
Two moments helped particular uses travel. The Boys, first released in 2019, has the character Billy Butcher repeatedly say "f---ing diabolical", according to the show's IMDb quote listings. And in September 2021 the TikTok Devious Licks trend, in which students stole or vandalised school property, used "Diabolical Licks" as an alternate hashtag; Axios reported the label as a way around moderation. Both put the word in front of many younger viewers, and both sit more than five centuries after the word entered English.
No single person is credited, the origin is well-documented.
Where it's popular
The "extremely bad" sense is British informal English. The playful reaction sense turns up in short-video comments, gaming chat, fan communities and Reddit, in the US and beyond.
Meaning depends on the object and the tone, not on one region. A British speaker complaining about trains and a creator's comment section can use the same word for different jobs.
How it caught on
- late 14th centuryThe related word diabolic is recorded in English, meaning "pertaining to the Devil".
- around 1500The Online Etymology Dictionary dates the adjective diabolical, with "befitting the devil" from the 1540s.
- 2019The Boys is first released; Billy Butcher's repeated "f---ing diabolical" appears in its quote listings.
- September 2021The TikTok Devious Licks trend uses "Diabolical Licks" as an alternate hashtag, according to Axios.
- September 28, 2026A TikTok captioned "You my mans but that sentence diabolical" with laughing emojis reaches 49,701 views.
Test yourself
Which diabolical is it?
0/21. A British friend texts "the trains were diabolical this morning". What do they mean?
2. Someone comments "that's diabolical" with laughing emojis under a video of a harmless prank. What is the usual reading?
Related slang
More word guides
How every generation says it
Questions people ask
What does it mean if someone is diabolical?
Literally, devil-like, cruel or wicked. In casual online use it often means someone did something outrageously clever or mischievous, like a prank or a brutal comeback. The relationship and the tone tell you whether it is an insult or teasing.
Why do people say diabolical now?
It works as a short, high-drama reaction to a prank, a chaotic video or an absurd food combination. The word itself dates to around 1500, and the slang use stretches its older meanings for comic effect.
Is diabolical positive or negative?
Negative. Cambridge defines it as "extremely bad or shocking" and as evil. Used playfully online it is exaggerated disapproval mixed with amusement or reluctant admiration, which makes it backhanded praise at most.
Is diabolical a cuss word?
It is a strongly negative adjective but not a swear word or a slur. It can be rude when aimed at someone as a serious accusation of cruelty. Between friends it can be playful, and in professional writing it fits only when you mean "extremely bad" or "morally wicked".
Is diabolical British slang?
One sense is. Oxford Learner's Dictionaries and Dictionary.com both list a British informal sense, "extremely bad", as in "the traffic was diabolical". The devilish sense and the online playful sense are used well beyond Britain.
Did The Boys make diabolical popular?
The show made one phrase, Billy Butcher's "f---ing diabolical", recognisable to many viewers. The word itself entered English around 1500.
The Online Etymology Dictionary dates diabolical to around 1500, so the word was in English for more than five centuries before TikTok existed.
- https://www.etymonline.com/word/diabolical
- https://dictionary.cambridge.org/us/dictionary/english/diabolical
- https://www.oxfordlearnersdictionaries.com/definition/english/diabolical
- https://www.collinsdictionary.com/dictionary/english/diabolical
- https://www.dictionary.com/browse/diabolical
- https://en.wiktionary.org/wiki/diabolical
- https://www.axios.com/2021/09/18/tiktok-devious-licks-challenge-schools-vandalize
- https://www.imdb.com/title/tt1190634/quotes/
- https://www.tiktok.com/@biggestswave/video/7690399073794264333
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