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Added 9 October 2026

pernicious

/pəˈnɪʃəs/ adjective

In Latin: perniciosus Wiktionary

adjective Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about pernicious at Wordnik → Where our words come from →

Exceedingly harmful.
Working or spreading in a hidden and usually injurious way.
glaucoma is an insidious disease

Origin

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

From Wiktionary, via Kaikki.org (CC BY-SA)

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