insidious

Meaning

1. Causing harm in a stealthy, often gradual, manner.
2. Intending to entrap; alluring but harmful.
3. (nonstandard) Treacherous.

Synonyms

treacherous

perfidious

subtle

deceitful

pernicious

cunning

crafty

underhand

guileful

sly

wily

serpentine

devious

sneaky

snaky

vulpine

artful

ill-intentioned

catty

conniving

deceptive

evil-minded

hangdog

malevolent

shady

shifty

sinister

smart

sneak

traitorous

treasonable

underhanded

Translations

insidieux

insidioso

insidioso

heimtückisch

arglistig

astuto

perfido

hinterhältig

pérfido

traiçoeiro

tückisch

hinterlistig

insidioso

hain

Pronounced as (IPA)

/ɪnˈsɪdi.əs/

Etymology

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”).