Dictionary definition for: Impenetrable
1. (a) not admitting of penetration or passage into or through; "an impenetrable fortress" "impenetrable rain forests"
2. (s) permitting little if any light to pass through because of denseness of matter; "dense smoke" "heavy fog" "impenetrable gloom"
3. (s) impossible to understand; "impenetrable jargon"
WordNet 2.1 Copyright Princeton University. All rights reserved.
