An impervious person or surface doesn't get affected by things that try to change them. Water can't seep into a rock face because it's impervious.
We often use "impervious" when talking about people who are stubborn and won't listen to others' opinions, but also in the literal sense of materials like water-repellent fabrics or rocks that don't absorb liquids. Think about a raincoat that's supposed to keep you dry - its material is impervious to water. It means the water can't get past it easily.
Unaffected or unable to be affected by something.
Example: The man was completely impervious to the deception we were trying.
