Pernicious

//pəˈnɪʃəs// adj

adj ·Moderate ·College level

Definitions

Adjective
  1. 1
    Causing much harm in a subtle way.

    "pernicious influence"

  2. 2
    swift; celeritous. obsolete
  3. 3
    Causing death or injury; deadly.
  4. 4
    Insidiously villainous: intending to cause harm, especially in a subtle way.
Adjective
  1. 1
    working or spreading in a hidden and usually injurious way wordnet
  2. 2
    exceedingly harmful wordnet

Synonyms

All synonyms
harmfulpestilentabandonedarrantatterybad

Example

More examples

"The Displacement of the idea that facts and evidence matter, by the idea that everything boils down to subjective interests and perspectives is — second only to American political campaigns — the most prominent and pernicious manifestation of anti-intellectualism in our time."

Etymology

Etymology 1

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

Etymology 2

Analyzable as pernīx ("swift") + -ious.

Related phrases

pernicious anemiapernicious scalepernicious anaemia

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.