1. intended to entrap or beguile: an insidious plan.
2. stealthily treacherous or deceitful: an insidious enemy.
3. operating or proceeding in an inconspicuous or seemingly harmless way but actually with grave effect: an insidious disease.
"sell-offs can be insidious in ways."
"factors can be insidious to controls."
"effects can be insidious."
"kinds can be insidious."
"diseases can be insidious."
This list can help you learn new vocabulary more quickly and be able explore other words more easily.