define: impervious
WordReference Random House Unabridged Dictionary of American English Â© 2016. imâ¢perâ¢viâ¢ous (im pÃ»râ²vÄ És), adj. 1  not permitting penetration or passage; impenetrable:The coat is impervious to rain.  incapable of being injured or impaired:impervious to wear and tear.