The main diabolical meaning is wicked, cruel or evil in a way that seems to come from the devil. A villain with a cold, careful plan to hurt people is diabolical.
The word has a lighter side too. In casual speech, especially in British English, people call bad food, awful traffic or a terrible referee diabolical, meaning simply very bad. Tone and setting reveal which sense a speaker intends, and this page shows you how to tell.
Entry at a glance
Meaning
Devilish and evil; informally, extremely badPart of speech
AdjectivePronunciation
dy-uh-BOL-ih-kulWord forms
diabolically (adverb), diabolic (older adjective)Origin
Late Latin diabolicus, from Greek diabolos, the devilOpposite
Angelic, saintly, kindRegister
Formal for evil; informal for awful
Three shades of the diabolical meaning
- Like the devil. Linked to the devil or to evil forces. Older religious writing uses it this way, for instance diabolical powers.
- Cruel and scheming. Wicked in a planned, clever way. A diabolical plot is not just bad; it is cunning and meant to cause harm.
- Very bad (informal). Terrible in quality. The wifi on this train is diabolical. No evil is meant here, only strong annoyance.
The second sense often carries a hint of grudging respect for the cleverness involved, which is why writers enjoy calling a puzzle or a twist diabolically clever.
Diabolical definition in action
- The detective realized the poisoner had planned every detail with diabolical care.
- Honestly, the queue at the passport office was diabolical this morning.
- The final exam had one diabolical question that nobody in our class solved.
- Prisoners in the old fort were kept in diabolical conditions, with no light or clean water.
- Our team's defending in the second half was diabolical, and the coach said so.
From the Greek word for slanderer
Diabolical grew from the older adjective diabolic, which came into English through Old French diabolique and Late Latin diabolicus. The source is the Greek diabolos, the word for the devil, which first meant an accuser or slanderer. It comes from a verb meaning to throw across, in the sense of throwing blame at someone.
The everyday English word devil shares this same Greek ancestor, so diabolical and devilish are close cousins in meaning and history.
Tone: when is it too strong?
In serious use, diabolical is a heavy word. Calling a real crime or act of torture diabolical expresses deep moral horror. It fits news reports, court summaries and history writing about cruelty.
In casual use, it is playful exaggeration, a form of hyperbole. Friends say that pun was diabolical with a grin. Be careful mixing the two: describing a colleague's report as diabolical in a work email may sound harsher than you intend, so weak or needs work is safer.
Nearby words and the opposite
| Word | Its particular flavor |
|---|---|
| Diabolical | Evil and scheming, or informally dreadful |
| Nefarious | Wicked and criminal, often in secret |
| Insidious | Spreading damage quietly before anyone notices |
| Fiendish | Cruel, or extremely tricky |
| Malicious | Meaning to hurt someone |
| Angelic | Opposite: pure, gentle and good |
Grammar and pairings
As an adjective, diabolical sits before a noun (a diabolical scheme) or follows a linking verb (the weather was diabolical). The adverb is diabolically: diabolically difficult, diabolically clever. Frequent partners include plan, plot, scheme, laugh, mastermind, conditions and performance. Comparisons such as more diabolical and most diabolical are fine. Plenty of other vivid adjectives wait on the everyday vocabulary hub.
Frequently asked questions
Is diabolical a negative word?
Yes, in almost every use. In the serious sense it means evil, and in the casual sense it means awful. The only softer use is diabolically clever, which praises skill while hinting at mischief.
What does diabolical mean in slang?
In relaxed British and Irish speech, diabolical means very bad or outrageous. People say a price, a meal or a decision is diabolical when they are shocked by how poor it is.
How do you pronounce diabolical?
Say dy-uh-BOL-ih-kul. The loud part is BOL, which rhymes with doll for most American speakers.
What is the difference between diabolical and diabolic?
They mean almost the same thing. Diabolic is the older form and now sounds formal or literary, while diabolical is far more common in speech and writing.
Can a person be diabolical?
Yes. A diabolical person is cruel and calculating, someone who plans harm with skill. In fiction, the word often describes a villain or mastermind.