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Showing results for nefarious. Search instead for nefariousl.
Definitions

nefarious

[ni-fair-ee-uhs] / nɪˈfɛər i əs /
ADJECTIVE
bad, sinful
Synonyms
STRONGEST
heinous horrible odious outrageous shameful vicious vile
WEAK
abominable atrocious base corrupt criminal degenerate depraved detestable dreadful evil execrable flagitious flagrant foul glaring gross infamous infernal iniquitous miscreant monstrous opprobrious perverse putrid rank rotten treacherous villainous wicked
Antonyms
STRONGEST
delightful gentle good kind magnificent nice pleasant pleasing wonderful
WEAK
honorable respectable virtuous worthy

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.

Here, siblings Mario and Luigi team with Princess Peach and Toad on an interstellar adventure and face off against the nefarious fire-breathing Bowser and his son.

From The Wall Street Journal • Mar. 29, 2026

Related: ‘Could a nefarious caregiver steal her money?’

From MarketWatch • Mar. 19, 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

They could be hiding a monster, but my gut tells me that what he’s hiding isn’t so nefarious.

From "Internment" by Samira Ahmed

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.