1. impenetrable; incapable of being penetrated and entered
1. Ayodhya means "unassailable", and this ancient city was so called because it was impervious to any enemy attack.
unable to be affected by
2. He refused to change his mind about the matter, being impervious to all attempts to reason with him.
in (not, opposite of)#per (through)#via (road)
"i m pervez (pervez musharraf)". no matter wat u say, i won't be affected!! im (not)+pravesh (enter) so unpenetrable. impervious = im-'not' + per-'completely' + vious 'via' [old] => not (completely via) => impossible to penetrate