Main Entry: im·pen·e·tra·ble

Pronunciation: \(ˌ)im-ˈpe-nə-trə-bəl\

Function: adjective

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

Date: 15th century

1 a : incapable of being penetrated or pierced b : inaccessible to knowledge, reason, or sympathy : impervious
2 : incapable of being comprehended : inscrutable

— im·pen·e·tra·bly \-blē\ adverb