Impenetrability

noun

1. The quality or condition of being impenetrable.
2. The inability of two bodies to occupy the same space at the same time.
3. The character or condition of being impenetrable; incapability of being penetrated, in any sense of that word.
4. In physics, specifically, that property of matter which prevents two bodies from occupying the same space at the same time; that property of matter by which it excludes all other matter from the space it occupies.
5. Quality of being impenetrable.