Lying in wait; watching an opportunity to insnare or entrap; deceitful; sly; treacherous; - said of persons; as, the insidious foe.
Intended to entrap; characterized by treachery and deceit; as, insidious arts.
Acting or proceeding unobserved or in a seemingly harmless manner, but slowly or eventually doing great damage; as, an insidious disease; an insidious plot.
Envious; malignant.
Worthy of envy; desirable; enviable.
Likely to or intended to incur or produce ill will, or to provoke envy or resentment; hateful; offensive; as, invidious distinctions.