Meaning & Definition of Impenetrable in English

1. Not admitting of penetration or passage into or through

• "An impenetrable fortress"

• "Impenetrable rain forests"

2. Permitting little if any light to pass through because of denseness of matter

• "Dense smoke"

• "Heavy fog"

• "Impenetrable gloom"

3. Impossible to understand

• "Impenetrable jargon"