Bu çok sinsi bir hastalık. Çok geç olana kadar onu fark etmezsiniz.
- That's a very insidious disease. You don't notice it until it's too late.
Ne kadar sinsi bir varsayım.
- What an insidious assumption.
Hansel and Gretel were lured by the witch's insidious gingerbread house.
The nurse always must be alert to signs of slow leak or insidious infiltration.