pernicious
Americanadjective
-
causing insidious harm or ruin; ruinous; injurious; hurtful.
pernicious teachings;
a pernicious lie.
- Synonyms:
- malicious, noxious, baneful, damaging, destructive, deleterious, detrimental, harmful
-
deadly; fatal.
a pernicious disease.
- Synonyms:
- lethal
-
Obsolete. evil; wicked.
adjective
-
wicked or malicious
pernicious lies
-
causing grave harm; deadly
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).
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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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.
The professionalization of youth sports—the incursion of for-profit companies strip-mining American childhood—hasn’t only wiped out recreational sports, it’s created a pernicious money culture.
From The Wall Street Journal ● Aug. 20, 2026
Lender losses drive a contraction of credit availability, the lifeblood of modern economies, leading to slowing economic activity and driving further iterations of the pernicious cycle.
From MarketWatch ● Jul. 9, 2026
He said conversion practices could be "particularly pernicious" in a church setting.
From BBC ● Jul. 4, 2026
In 2026, it is 100 years since George Minot and William Murphy reported that a liver-rich diet could treat pernicious anemia, then a frequently fatal disease.
From Science Daily ● Jun. 25, 2026
Something deeper, more pernicious was at work here: a wide division between the wealthy and the poor that was made worse by fear.
From "The Great Fire" by Jim Murphy
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
