1
[ adjective ] not admitting of penetration or passage into or through

Examples

"an impenetrable fortress" "impenetrable rain forests"

Related terms

penetrable dense

2
[ adjective ] permitting little if any light to pass through because of denseness of matter

Synonyms

dense heavy

Examples

"dense smoke" "heavy fog" "impenetrable gloom"

Related terms

thick

3
[ adjective ] impossible to understand

Examples

"impenetrable jargon"

Related terms

incomprehensible

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