The difference between Impenetrable and Pregnable

When used as adjectives, impenetrable means not penetrable, whereas pregnable means vulnerable to attack.

check bellow for the other definitions of Impenetrable and Pregnable

Impenetrable as an adjective:

Not penetrable.

Examples:

"The fortress is impenetrable, so it cannot be taken."
Impenetrable as an adjective (figuratively):

Incomprehensible; fathomless; inscrutable.

Examples:

"Business jargon makes this document impenetrable, I can't understand it."
Impenetrable as an adjective:

Opaque; obscure; not translucent or transparent.

Examples:

"When night falls, she cloaks the world in impenetrable darkness."