10 letters · 14 points in Scrabble
adjective exceedingly harmful
adjective working or spreading in a hidden and usually injurious way
originFrom Middle English, from Old French pernicios, from Latin perniciōsus (“destructive”), from perniciēs (“destruction”), from per (“through”) + nex (“slaughter, death”).
Etymology from Wiktionary, CC BY-SA 3.0