Definitions

pernicious

[per-nish-uhs] / pərˈnɪʃ əs /

ADJECTIVE

bad, hurtful

Synonyms

STRONGEST

damaging dangerous deadly destructive detrimental devastating harmful lethal malicious nefarious noxious poisonous ruinous toxic virulent

WEAK

baleful deleterious evil fatal iniquitous injurious killing maleficent malevolent malign malignant miasmatic miasmic mortal noisome offensive pestiferous pestilent pestilential prejudicial sinister venomous wicked

Antonyms

STRONGEST

advantageous assisting beneficial benevolent good harmless healthy helpful kind nonpoisonous wholesome

WEAK

innocuous lovable loving

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.

What frightens scientists more than the sheer numbers are that the cuts are arbitrary and manifestly pernicious.

From Los Angeles Times • Jun. 11, 2026

Higher inflation has a particularly pernicious effect on U.S. households.

From Barron's • Jun. 10, 2026

Dahlia Lithwick: Election law expert Rick Hasen just described this as “one of the most pernicious and damaging Supreme Court decisions of the past century.”

From Slate • Apr. 30, 2026

“But when things are mostly right but sometimes wrong, that’s the most pernicious one.”

From The Wall Street Journal • Apr. 14, 2026

And yet a pernicious seed had been planted—a perception of me as disgruntled and vaguely hostile, lacking some expected level of grace.

From "Becoming" by Michelle Obama

Vocabulary lists containing pernicious

Romeo and Juliet

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300 Most Difficult "SAT" Words

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The Tragedy of Hamlet, Prince of Denmark

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