the GNU version of the Collaborative International Dictionary of English
adj. Not pervious; impervious.
The Century Dictionary and Cyclopedia
Impervious.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not admitting of passage or capable of being affected
Word Usage
"Merrington had received the information with the imperviable dogmatism of the official mind, strong in the belief in its own infallibility, resentful of advice or suggestion as an attempt to weaken its dignity."