01 a. Incapable of being penetrated or pierced; not admitting the passage of other bodies; not to be entered; impervious; as, an impenetrable shield.
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1.
Incapable of being penetrated or pierced; not admitting the passage of other bodies; not to be entered; impervious; as, an impenetrable shield.“Highest woods impenetrable To star or sunlight.” — Milton.
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2.
Having the property of preventing any other substance from occupying the same space at the same time.(Physics)
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3.
Inaccessible, as to knowledge, reason, sympathy, etc.; unimpressible; not to be moved by arguments or motives; as, an impenetrable mind, or heart.“They will be credulous in all affairs of life, but impenetrable by a sermon of the gospel.” — Jer. Taylor.