Meaning of “impervious” - Learner’s Dictionary

impervious

adjective uk us /ɪmˈpɜːviəs/
EFFECT

not affected by something:

She was impervious to the pain.
LIQUID formal

Impervious material does not let liquid into or through it:

impervious rock

(Definition of “impervious” from the Cambridge Learner’s Dictionary © Cambridge University Press)