impenetrable

/(ˌ)im-ˈpe-nə-trə-bəl/

Middle English impenetrabel, from Middle French impenetrable, from Latin impenetrabilis, from in- + penetrabilis penetrable

adjective

  1. incapable of being penetrated or pierced

  2. inaccessible to knowledge, reason, or sympathy : impervious

  3. incapable of being comprehended : inscrutable