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

There’s a pernicious form of viral video that’s reshaping our collective reality, and it’s not even related to artificial intelligence.

From Slate • May 6, 2026

That’s not a new concept, but it’s become all the more pernicious.

From Salon • May 1, 2026

Its consequences for the history of science have been, it seems to me, pernicious.

From "The Invention of Science" by David Wootton

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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