The nefarious meaning is "wicked" or "criminal": a nefarious act or person is morally bad, usually in a deliberate, scheming way. Smuggling, fraud, blackmail and secret plots are all described as nefarious.
The word has a slightly dramatic, storybook feel, which is why you hear it about movie villains and in news stories about scams, but also in jokes ("What nefarious plan are you hatching with that leftover pizza?"). Below you will find the nefarious definition, its Latin roots, sample sentences and the look alikes that trip people up.
Entry at a glance
Meaning
Extremely wicked, villainous or criminalPart of speech
AdjectivePronunciation
nih-FAIR-ee-uhsWord forms
nefariously (adverb), nefariousness (noun)Origin
Latin nefarius, from nefas, "a crime against divine law"; in English from around 1600Opposite
Honest, upright, virtuous, benevolentRegister
Formal or literary; often used playfully
What does nefarious mean?
If you had to define nefarious in three words, try wicked on purpose. It is not a mistake or bad luck; there is intent behind it. The word usually suggests:
- Serious wrongdoing, often crime: theft, fraud, spying, trafficking.
- A plan or purpose: people talk of nefarious schemes, plots, motives and activities.
- Secrecy: the wrongdoer often tries to hide what they are doing.
Because of that last point, people sometimes ask whether someone has "nefarious intentions" when they suspect a hidden bad purpose behind an innocent looking action.
Nefarious meaning in real sentences
- Police believe the warehouse was used for nefarious purposes, including storing stolen phones.
- The email looked official, but its nefarious goal was to steal your bank password.
- In the cartoon, the villain twirls his moustache while explaining his nefarious plan.
- My little brother crept toward the cookie jar with obviously nefarious intent.
- Investigators uncovered a nefarious network that sold fake medicines online.
Scams like this are close cousins of phishing, where the nefarious aim is hidden behind a friendly message.
Roots in Roman law and religion
English borrowed nefarious around 1600 from Latin nefarius, "wicked, abominable, impious". The Latin comes from nefas, which joins ne, "not", with fas, roughly "what is right or allowed by divine law". So something nefarious was originally an offence not just against people but against the sacred order.
That history explains why the word still feels heavier than plain bad. For related ideas about breaking sacred rules, see blasphemy.
How to use nefarious naturally
The word is an adjective and usually sits before a noun. Common pairings include:
- nefarious activities, nefarious purposes, nefarious ends
- nefarious scheme, nefarious plot, nefarious plan
- nefarious actors (common in security and policy writing for people who cause harm)
It can follow a verb too: "Their motives were nefarious." Since it sounds formal, it adds drama or humour in casual speech. Saying a cat has "nefarious plans" for the curtains is a joke built on the gap between the grand word and the small crime.
Nefarious next to similar words
| Word | Shade of meaning |
|---|---|
| Nefarious | Wicked and usually criminal, with a deliberate plan |
| Sinister | Giving a feeling that something evil may happen; about atmosphere |
| Malicious | Wanting to hurt someone; focuses on the intent, see malice |
| Diabolical | Devilishly cruel or cunning; even more dramatic |
| Insidious | Damaging gradually and out of sight, often with no villain behind it |
| Egregious | Shockingly bad, often an obvious error, not necessarily evil |
A quick test: if the badness comes from a wrongdoer's deliberate scheme, nefarious is the right choice. If the harm creeps up unseen, try insidious.
Common slips
People occasionally use nefarious to mean "numerous" or "various", perhaps because of the sound of multifarious. That is a mistake: nefarious always means wicked. Another slip is spelling it nefarius, the Latin form. The English word ends in -ious. Finally, avoid it for mild rudeness. A colleague who forgets to say thank you is impolite, not nefarious. More useful words are collected in our everyday vocabulary list.
Frequently asked questions
Is nefarious a strong word?
Yes. It means very wicked or criminal, so it is stronger than bad or naughty. In casual speech people use it jokingly precisely because it sounds so serious.
How do you pronounce nefarious?
Say nih-FAIR-ee-uhs. Lean on FAIR, the second beat, sounded just like the word fair.
What does nefarious intent mean?
It means a hidden wicked or criminal purpose behind an action. Security teams, police and lawyers use it when they suspect someone is planning harm.
Can a person be nefarious?
Yes. A nefarious person is a villain who deliberately does evil or criminal things, though the word is more often attached to plans, deeds and motives.
What is the opposite of nefarious?
Words such as virtuous, honourable, honest and benevolent describe good intentions and behaviour, the reverse of nefarious.
What is the difference between nefarious and malicious?
Malicious focuses on the wish to hurt someone. Nefarious focuses on the wickedness of the act or scheme itself, often a crime.