impenetrable

adj 1: not admitting of penetration or passage into or through; "an

impenetrable fortress"; "impenetrable rain forests"

[ant: {penetrable}]

2: permitting little if any light to pass through because of

denseness of matter; "dense smoke"; "heavy fog";

"impenetrable gloom" [syn: {dense}, {heavy}]

3: impossible to understand; "impenetrable jargon"