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Synonyms

pernicious

American  
[per-nish-uhs] / pərˈnɪʃ əs /

adjective

  1. causing insidious harm or ruin; ruinous; injurious; hurtful.

    pernicious teachings;

    a pernicious lie.

    Synonyms:
    malicious, noxious, baneful, damaging, destructive, deleterious, detrimental, harmful
  2. deadly; fatal.

    a pernicious disease.

    Synonyms:
    lethal
  3. Obsolete. evil; wicked.


pernicious British  
/ pəˈnɪʃəs /

adjective

  1. wicked or malicious

    pernicious lies

  2. causing grave harm; deadly

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of pernicious

First recorded in 1515–25; from Latin perniciōsus “ruinous,” from pernici(ēs) “ruin” (from per- per- + -nici-, combining form of nex “death, murder” + -ēs, noun suffix) + -ōsus -ous

Explanation

Pernicious means harmful and subtle, such as a poison gas that causes illness in those exposed to it over the course of years. Pernicious comes from the Latin perniciosus, "destructive," which in turn comes from pernicies, "death" or "ruin." You might have heard your parents and teachers talk about the pernicious effects of watching too much TV and playing video games all day — they'll turn your brain to mush (allegedly).

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Vocabulary lists containing pernicious

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.

An important first step toward finding answers can be found in a paper cited in the V-Dem report, "Pernicious Polarization, Autocratization and Opposition Strategies."

From Salon • Apr. 3, 2022

The Hatch Act, also known as the “Act to Prevent Pernicious Political Activities,” was signed into law in 1939 by President Franklin D. Roosevelt.

From Washington Post • Jun. 13, 2019

"Pernicious anemia is an autoimmune disease that starts in the stomach and that impairs the body's ability to absorb food efficiently," physician and medical historian Dr. John Sotos told CBS News.

From US News • Jul. 18, 2016

Pernicious anemia could explain many of her problems, mental and physical, he reported in an article published last week in Perspectives in Biology and Medicine.

From Seattle Times • Jul. 9, 2016

As Pernicious, he talks things that are false with a view to injure his neighbour, or any one towards whom he has an evil feeling.

From Talkers With Illustrations by Bate, John