a. | 1. | Incapable of being penetrated or pierced; not admitting the passage of other bodies; not to be entered; impervious; |
2. | (Physics) Having the property of preventing any other substance from occupying the same space at the same time. | |
3. | Inaccessible, as to knowledge, reason, sympathy, etc.; unimpressible; not to be moved by arguments or motives; |
Adj. | 1. | impenetrable - not admitting of penetration or passage into or through; "an impenetrable fortress"; "impenetrable rain forests" Antonyms: penetrable - admitting of penetration or passage into or through; "a penetrable wall"; "penetrable defenses" |
2. | impenetrable - permitting little if any light to pass through because of denseness of matter; "dense smoke"; "heavy fog"; "impenetrable gloom" | |
3. | impenetrable - impossible to understand; "impenetrable jargon" |