nefarious
Americanadjective
adjective
Other Word Forms
- nefariously adverb
- nefariousness noun
- unnefarious adjective
- unnefariously adverb
- unnefariousness noun
Etymology
Origin of nefarious
First recorded in 1595–1605; from Latin nefārius “wicked, vile,” equivalent to nefās “offense against divine or moral law” (from ne-, negative prefix + fās “law, right”) + -ius -ious
Explanation
Describe a person's actions as nefarious if they are evil or wicked. Batman and Superman are always fighting evildoers and stopping their nefarious plots. Nefarious comes from the Latin nefas "crime, impiety." If something is nefarious, it is criminal, evil, malicious and wicked. Thinking of superheroes can help you remember the meaning of the word, but it is often used in much less exciting circumstances. News reporters investigate corrupt politicians in order to uncover the nefarious activities. And, if you don't pay for your downloaded music, you have gotten it by nefarious means.
Vocabulary lists containing nefarious
Grade 9, List 4
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
By comparison with some of the nefarious plotters in that show, Titus is a bit of an also-ran—at least at first.
From The Wall Street Journal • Apr. 1, 2026
Let him know that there’s a chance this is a romance scam/honey trap and that even the smartest people get hoodwinked by nefarious characters who take advantage of their loneliness.
From MarketWatch • Mar. 23, 2026
But agents have to be given powerful permissions to do their jobs, and we are already seeing this being exploited in potentially nefarious ways in what are called prompt injection attacks.
From Barron's • Feb. 17, 2026
A nefarious hacker could have easily installed a virus on to my machine without me having to do anything.
From BBC • Feb. 12, 2026
Words like: viscous, impunity, paroxysm, unctuous, nefarious, onanistic, perfidious, lugubrious.
From "Hole in My Life" by Jack Gantos
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
