impenetrable (not comparable)
- Not penetrable.
- The fortress is impenetrable, so it cannot be taken.
2012 May 3, John Branch, “Snow Fall : The Avalanche at Tunnel Creek”, New York Time:
- The avalanche spread and stopped, locking everything it carried into an icy cocoon. It was now a jagged, virtually impenetrable pile of ice, longer than a football field and nearly as wide.
- (figuratively) Incomprehensible; inscrutable.
- Business jargon makes this document impenetrable, I can't understand it.