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
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
It’s “a persistent pattern generally attached to nefarious tricks such as channel stuffing, aggressive revenue recognition or extended payment terms used as sales concessions,” Burry said in a recent Substack post.
From MarketWatch • Feb. 27, 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
What she had made was called a grappling hook, which is something used for climbing up the sides of buildings, usually for a nefarious purpose.
From "The Bad Beginning" by Lemony Snicket
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.
