Definition of IMPENETRABLE

impossible to get through or into <the ancient temple was surrounded by vast stretches of impenetrable jungle>
Synonyms impassable (also impassible), impermeable, impervious, impregnable
not allowing penetration (as by gas, liquid, or light) <the container of toxic waste has an impenetrable seal to prevent leaks>
Near Antonyms absorbent, leaky, porous, unsealed

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