pernicious

From Middle English, from Old French pernicios, from Latin perniciōsus (“destructive”), from perniciēs (“destruction”), from per (“through”) + nex (“slaughter, death”).

• IPA^(key): /pəˈnɪʃəs/

• Audio (US)

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  Rhymes: -ɪʃəs

pernicious (comparative more pernicious, superlative most pernicious)

1. Causing much harm in a subtle way.
   • 1911, Emma Goldman, The Hypocrisy of Puritanism

     Puritanism no longer employs the thumbscrew and lash; but it still has a most pernicious hold on the minds and feelings of the American people.

   • 2017 March 22, Jacob Kastrenakes, “Medium launches memberships for $5 per month”, in The Verge‎:

     In January, the company laid off a third of its staff and renounced ads as a pernicious influence on the world, without mentioning that Google and Facebook are so good at ads there’s hardly room for anyone else to compete.

2. Causing death or injury; deadly.

   Synonym: attery

• perniciousness
• perniciously

• pernicious anemia

• superionic