nefarious
Americanadjective
adjective
Other Word Forms
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.
The Justice Department, Federal Bureau of Investigation and existing authorities are sufficient to hold accountable bad actors using AI for nefarious purposes, he said.
From The Wall Street Journal ● Sep. 29, 2026
Anthropic, the AI tech company behind Claude, released a report Thursday detailing how bad actors have attempted to use its products for nefarious ends, from scams and mass surveillance to biological weapons development.
From Salon ● Sep. 11, 2026
He has said he did not know about Epstein's "nefarious activity until Epstein was charged with trafficking in July 2019".
From BBC ● Sep. 3, 2026
Then there’s the more nefarious activities – I’ve heard of researchers deliberately moving specimens to make them hard to find so other researchers cannot examine them, and occasionally things are stolen from collections.
From Science Daily ● Aug. 7, 2026
The Criminal Element spoke often, and passionately, about the nefarious activities that every human being is capable of.
From "Flora & Ulysses: The Illuminated Adventures" by Kate DiCamillo
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Get a wordDefinitions 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.
