pernicious

adjective

pər-ˈni-shəs 
Definition of pernicious
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
  • California was among dozens of states that sued Meta in 2023, alleging in a lawsuit that the social media giant intentionally designed harmful and addictive features to hook children while misleading the public about the dangers.
    — Sonja Sharp, Los Angeles Times, 26 Aug. 2026
  • The report said the company was strengthening its research infrastructure, increasing monitoring and improving safeguards designed to prevent harmful or unintended behavior.
    — Reuters, NBC news, 26 Aug. 2026
Definition of harmful
Adjective
  • The desert’s location on the southern border has led to many migrants attempting to cross it by using dangerous backcountry routes, the experts said.
    — Emma Tucker, CNN Money, 24 Aug. 2026
  • Rather, this is a dangerous, shape-shifting synthetic entity that ravaged their entire planet.
    — Siddhant Adlakha, Vulture, 24 Aug. 2026
Definition of dangerous
Adjective
  • New redistricting maps There’s also the detrimental effects for Democrats of recent redistricting in Florida.
    — Joshua Ceballos, Miami Herald, 22 Aug. 2026
  • The math curriculum, in my view, has been detrimental to many students.
    — Olivia Young, CBS News, 21 Aug. 2026
Definition of detrimental
Adjective
  • Missing, say, 30 games would likely not be as damaging as missing half a season, or a whole season.
    — Evan Drellich, New York Times, 26 Aug. 2026
  • Strong El Niño events, such as the one revving up in the tropical Pacific, have rarely spared the Golden State from significant and damaging consequences.
    — Andrew Freedman, CNN Money, 25 Aug. 2026
Definition of damaging
Adjective
  • Then England attracted adverse attention for openly drinking in the Queensland resort of Noosa when 2-0 down in a one-sided Ashes series in Australia.
    — Paul Newman, New York Times, 23 Aug. 2026
  • Women with high occupational heat exposure were roughly twice as likely to suffer a miscarriage or stillbirth as those working in cooler conditions, and faced elevated risks of adverse birth outcomes overall.
    — Catarina Rolfsdotter-Jansson, Forbes.com, 22 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 27 Aug. 2026.

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