pernicious

adjective per·ni·cious \pər-ˈni-shəs\

: causing great harm or damage often in a way that is not easily seen or noticed

Full Definition of PERNICIOUS

: highly injurious or destructive : deadly

archaic : wicked

— per·ni·cious·ly adverb

— per·ni·cious·ness noun

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Examples of PERNICIOUS

The notion that poll data are a legitimate form of news has to be one of the most pernicious tenets of late-twentieth-century American journalism … —Barbara Ehrenreich, Nation, 20 Nov. 1995
The more it [the Papacy] took part in the temporal conflicts with consistently pernicious result, the more impotent among the monarchs it revealed itself … —Barbara W. Tuchman, The March of Folly, 1984
At its most pernicious, paper entrepreneurialism involves little more than imposing losses on others for the sake of short-term profits for the firm. —Robert B. Reich, Atlantic, March 1983
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Origin of PERNICIOUS

Middle English, from Anglo-French, from Latin perniciosus, from pernicies destruction, from per- + nec-, nex violent death — more at noxious

First Known Use: 15th century

Related to PERNICIOUS

Synonyms: adverse, bad, baleful, baneful, damaging, dangerous, deleterious, detrimental, evil, hurtful, ill, injurious, mischievous, nocuous, noxious, harmful, prejudicial, wicked

Antonyms: anodyne, benign, harmless, hurtless, innocent, innocuous, inoffensive, safe

Synonym Discussion of PERNICIOUS

pernicious, baneful, noxious, deleterious, detrimental 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>. baneful implies injury through poisoning or destroying <the baneful notion that discipline destroys creativity>. noxious applies to what is both offensive and injurious to the health of a body or mind <noxious chemical fumes>. deleterious applies to what has an often unsuspected harmful effect <a diet found to have deleterious effects>. detrimental implies obvious harmfulness to something specified <the detrimental effects of excessive drinking>.