1 : incapable of being taken by assault : unconquerable an impregnable fortress. 2 : unassailable also : impenetrable impregnable walls.

Can a person be impregnable?

If you say that a person or group is impregnable, or their position is impregnable, you think they cannot be defeated by anyone. ... the company's impregnable market position.

What does impregnable domain mean?

If you describe a building or other place as impregnable, you mean that it cannot be broken into or captured.