impenetrable Definition

impenetrable
adj

1. Incapable of being entered or passed through.

Example: an impenetrable jungle
Thesaurus: dense, impervious, compact, hard.
2. Not capable of being understood or explained; unfathomable or inscrutable.

Example: I found his argument completely impenetrable
Thesaurus: incomprehensible, unintelligible, unfathomable, inscrutable.
3. Not capable of receiving or being touched by intellectual ideas and influences.

Example: impenetrable ignorance
4. Unable to be seen through; gloomy.

Example: sank into impenetrable despair

Derivative: impenetrability
noun

Derivative: impenetrably
adverb

Etymology: 15c: from Latin impenetrabilis.