1. the quality or state of being impossible to penetrate or pass through
Usage: commonly used in physics and philosophy
2. the quality of being impossible to understand or comprehend

Examples

• The impenetrability of the fortress walls made it nearly impossible for invaders to breach.
• The dense fog created an impenetrability that made it hard to see more than a few feet ahead.
• The impenetrability of the ancient text frustrated scholars for centuries.
• Modern armor is designed with impenetrability in mind to protect soldiers.
• The impenetrability of her expression left everyone guessing about her true feelings.
• In physics, impenetrability refers to the property that two objects cannot occupy the same space.