impenetrable

American  

[im-pen-i-truh-buhl] / ɪmˈpɛn ɪ trə bəl /

adjective

1. not penetrable; that cannot be penetrated, pierced, entered, etc.

2. inaccessible to ideas, influences, etc.

3. incapable of being understood; inscrutable; unfathomable.

   an impenetrable mystery.

   Synonyms:

   hidden, obscure, mysterious, incomprehensible

   Antonyms:

   lucid, clear

4. Physics. possessing impenetrability.

---

impenetrable British  

/ ɪmˈpɛnɪtrəbəl /

adjective

1. incapable of being pierced through or penetrated

   an impenetrable forest

2. incapable of being understood; incomprehensible

   impenetrable jargon

3. incapable of being seen through

   impenetrable gloom

4. not susceptible to ideas, influence, etc

   impenetrable ignorance

5. physics (of a body) incapable of occupying the same space as another body

---

Other Word Forms

• impenetrability noun
• impenetrableness noun
• impenetrably adverb

Etymology

Origin of impenetrable

1425–75; late Middle English impenetrabel < Latin impenetrābilis. See im- ², penetrable

Example Sentences

“An impenetrable wall of disinfectant for your face.”

From Literature

That style is dense, intricate and sometimes impenetrable, and Ms. Serpell means to celebrate its difficulties while guiding us through them.

From The Wall Street Journal

The primary difference between public and private prisons, experts told Salon, is that private prisons operate in an even more impenetrable black box than public prisons.

From Salon

The idea is that they could overwhelm enemies or erect impenetrable defenses against threats with minimal human input.

From The Wall Street Journal

A poorly cleared corner followed by an unfortunate deflection proved fatal to the hitherto impenetrable Parisian defence.

From Barron's

Related Words

• arcane
• baffling
• inexplicable
• inscrutable
• mysterious
• unaccountable
• unfathomable
• unintelligible