pernicious

adjective

pər-ˈni-shəs How to pronounce pernicious (audio)
Definition of perniciousnext
as in harmful
causing or capable of causing harm the pernicious effects of illegal narcotics on society

Synonyms & Similar Words

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Antonyms & Near Antonyms

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How is the word pernicious different from other adjectives like it?

Some common synonyms of pernicious are baneful, deleterious, detrimental, and noxious. While all these words mean "exceedingly harmful," pernicious implies irreparable harm done through evil or insidious corrupting or undermining.

the claim that pornography has a pernicious effect on society

When is baneful a more appropriate choice than pernicious?

The words baneful and pernicious are synonyms, but do differ in nuance. Specifically, baneful implies injury through poisoning or destroying.

the baneful notion that discipline destroys creativity

When could deleterious be used to replace pernicious?

While in some cases nearly identical to pernicious, deleterious applies to what has an often unsuspected harmful effect.

a diet found to have deleterious effects

In what contexts can detrimental take the place of pernicious?

The meanings of detrimental and pernicious largely overlap; however, detrimental implies obvious harmfulness to something specified.

the detrimental effects of excessive drinking

When is it sensible to use noxious instead of pernicious?

While the synonyms noxious and pernicious are close in meaning, noxious applies to what is both offensive and injurious to the health of a body or mind.

noxious chemical fumes

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of pernicious But even with federal legislation prohibiting discrimination, the pernicious virus of bias infects too many institutions. — New York Daily News Editorial Board, New York Daily News, 19 June 2026 What frightens scientists more than the sheer numbers are that the cuts are arbitrary and manifestly pernicious. — Business Columnist, Los Angeles Times, 11 June 2026 Nine crucial years of expansion and solidification of the pernicious institution went by, speeding the nation’s road toward a grinding war. — Literary Hub, 3 June 2026 Microplastics are tiny fragments, that can be as small as 1/25,000th of an inch (1 micrometer) and are a pernicious part of the plastic pollution crisis. — Laura Paddison, CNN Money, 29 Apr. 2026 See All Example Sentences for pernicious
Recent Examples of Synonyms for pernicious
  1. harmful
  2. dangerous
  3. detrimental
  4. damaging
  5. adverse
Adjective
  • But fasted training isn’t necessarily harmful to muscle gain, Maroldi adds.
    — Daryl Austin, USA Today, 2 Sep. 2026
  • What’s considered harmful to minors can be subjective, and this is where experts believe laws requiring age verification can run afoul of the First Amendment.
    — ABC News, ABC News, 1 Sep. 2026
Definition of harmful
Adjective
  • Heaping credit onto Espada is dangerous, but so is blaming him for every game that goes awry.
    — Chandler Rome, New York Times, 31 Aug. 2026
  • That’s a dangerous prospect for any country, but especially for Singapore, crammed into a space smaller than New York City.
    — Angelica Ang, Fortune, 30 Aug. 2026
Definition of dangerous
Adjective
  • Being full of yourself isn’t detrimental but necessary for survival.
    — Angelica Jade Bastién, Vulture, 27 Aug. 2026
  • The settlement also requires limits on features that some experts believe are detrimental to teenagers’ self-esteem and self-image.
    — Kaitlyn Tiffany, The Atlantic, 26 Aug. 2026
Definition of detrimental
Adjective
  • It’s also infused with an antioxidant-rich blend of Australian botanicals and a blue light complex to help protect skin from the damaging blue light emitted by screens and devices.
    — Alison Abbey Hudak, Footwear News, 1 Sep. 2026
  • Hamza Iqbal, 20; Rehan Khan, 19; Judex Atshatshi; and Saif Ali, both 18, faced a charge of destroying or damaging property and of being reckless as to whether life would be endangered.
    — Los Angeles Times, Los Angeles Times, 28 Aug. 2026
Definition of damaging
Adjective
  • Ustel said the ferry faced adverse weather conditions and began taking in water just 15 minutes after departure.
    — ABC News, ABC News, 30 Aug. 2026
  • The report identified adverse effects on dozens of historic properties, including the Lincoln Memorial, Washington Monument and other landmarks.
    — Amelia Lucas, CNBC, 29 Aug. 2026
Definition of adverse

Browse Nearby Words

perms
pernicious
pernickety
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Cite this Entry

“Pernicious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/pernicious. Accessed 5 Sep. 2026.

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