Added 9 October 2026
insidious
/ɪnˈsɪdi.əs/ adjective
In Latin: insidiosus Wiktionary
adjective Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about insidious at Wordnik → Where our words come from →
Origin
From Middle French insidieux, from Latin īnsidiōsus (“cunning, artful, deceitful”), from īnsidiae (“a lying in wait, an ambush, artifice, stratagem”) + -ōsus, from īnsideō (“to sit in or on”), from in (“in, on”) + sedeō (“to sit”).
From Wiktionary, via Kaikki.org (CC BY-SA)