impenetrable

adjective

im·​pen·​e·​tra·​ble (ˌ)im-ˈpe-nə-trə-bəl 

1

a

: incapable of being penetrated or pierced

b

: inaccessible to knowledge, reason, or sympathy : impervious

2

: incapable of being comprehended : inscrutable

impenetrably

(ˌ)im-ˈpe-nə-trə-blē 

adverb

Synonyms

• impassable
• impassible
• impermeable
• impervious
• impregnable

Examples of impenetrable in a Sentence

The fort's defenses were thought to be impenetrable.

the ancient temple was surrounded by vast stretches of impenetrable jungle

Recent Examples on the Web

Despite the physical and emotional toll their work extracts, the women who live at the parlor create an impenetrable sisterhood. —Andreas Wiseman, Deadline, 26 Sep. 2024

The market had become all but impenetrable after mortgage rates went from historic lows in 2020 to their highest levels in a generation last year. —Allison Morrow, CNN, 18 Sep. 2024

There are, however, people in this apathetic crowd who are burning up on the inside with shame at what has happened to their beloved country, at the impenetrable indifference and docility of the others. —Andrei Kolesnikov, Foreign Affairs, 17 May 2024

Like me, Steele has privileges of race and financial security, but those are not impenetrable shields against the kinds of things that can happen to trans women in sparsely populated places. —Samantha Allen, Them, 12 Sep. 2024

Word History

Etymology

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

First Known Use

15th century, in the meaning defined at sense 1a

Kids Definition

impenetrable

adjective

im·​pen·​e·​tra·​ble (ˈ)im-ˈpen-ə-trə-bəl 

1

: impossible to get through or into

impenetrable walls

impenetrable jungle

2

: impossible to understand

an impenetrable mystery

impenetrability

(ˌ)im-ˌpen-ə-trə-ˈbil-ət-ē

noun

impenetrably

(ˈ)im-ˈpen-ə-trə-blē 

adverb