1) Complexity 2) Density 3) Impenetrableness 4) Imperviousness 5) Opacity 
In metaphysics, impenetrability is the name given to that quality of matter whereby two bodies cannot occupy the same space at the same time.The philosopher John Toland argued that impenetrability and extension were sufficient to define matter, a contention strongly disputed by Gottfried Wilhelm Von Leibnez. Locke considered impenetrability to be ...
• (n.) Quality of being impenetrable. • (n.) That property in virtue of which two portions of matter can not at the same time occupy the same portion of space. • (n.) Insusceptibility of intellectual or emotional impression; obtuseness; stupidity; coldness.
Im·pen`e·tra·bil'i·ty noun [ Confer French impénétrabilité .] 1. Quality of being impenetrable. 2. (Physics) That property in virtue of which two portions of matter can not at the same time occupy the same portion of space. 3. Insusceptibility of intellectu...
[n] - resistance to penetration by a liquid 2. [n] - incomprehensibility by virtue of being too dense to understand
noun incomprehensibility by virtue of being too dense to understandimperviousness noun the quality of being impenetrable (by people or light or missiles etc.)
the state or quality of being impenetrable. · that property of matter by virtue of which two bodies cannot occupy the same space simultaneously.