Standard Lemma guide

impenetrable

adj · noun · 7 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • /ɪmˈpɛnətɹəbəl/
  • /ɪmˈpɛnɪtɹəbəl/
  • Southern-England: Recorded audio is listed in the source snapshot.
  • UK: Recorded audio is listed in the source snapshot.
  • CMU ARPABET: IH2 M P EH1 N AH0 T R AH0 B AH0 L Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.

1

adj

Meaning 1

Not penetrable.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

Examples

  • The fortress is impenetrable, so it cannot be taken.

Meaning relationships

Synonyms: impermeable, impregnable

Antonyms: penetrable, permeable, pregnable

2

adj

Meaning 2

Opaque; obscure; not translucent or transparent.

Definition source: English Wiktionary via Wiktextract

Usage: not-comparable

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

adj

Meaning 3

Incomprehensible; fathomless; inscrutable.

Definition source: English Wiktionary via Wiktextract

Usage: figuratively, not-comparable

Examples

  • Business jargon makes this document impenetrable—I can’t understand it.

Meaning relationships

Synonyms: unfathomable, abstruse, Chinese, dense, enigmatic, fathomless, Greek, inapprehensible, incognizable, incomprehensible, ineffable, inenubilable, inexplicable, impenetrable, insensible, inscrutable, insoluble, insolvable, mysterious, nonunderstandable, obscure, retruse, tenebrose, thick, undecipherable, undiscoverable, unexplainable, ungraspable, unintelligible, unknowable, ununderstandable

Antonyms: fathomable, apprehensible, clear, limpid, comprehensible, explainable, explicable, explicatable, graspable, illuminable, intelligible, lucid, pellucid, perspicuous, straightforward, tangible, understandable

4

noun

Meaning 4

A person not openly given to friendship.

Definition source: English Wiktionary via Wiktextract

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

5

adjective

Meaning 5

not admitting of penetration or passage into or through

Definition source: Princeton WordNet 3.0

Examples

  • an impenetrable fortress
  • impenetrable rain forests

Meaning relationships

Synonyms: none provided

Antonyms: penetrable

6

adjective satellite

Meaning 6

impossible to understand

Definition source: Princeton WordNet 3.0

Examples

  • impenetrable jargon

Meaning relationships

Synonyms: none provided

Antonyms: none provided

7

adjective satellite

Meaning 7

permitting little if any light to pass through because of denseness of matter

Definition source: Princeton WordNet 3.0

Examples

  • dense smoke
  • heavy fog
  • impenetrable gloom

Meaning relationships

Synonyms: dense, heavy

Antonyms: none provided

History

Etymology

From Middle English inpenetrabel, inpenetrabyle, from Middle French impenetrable or directly from its etymon, Latin impenetrābilis. By surface analysis, im- + penetrable.

Across languages

Translations

34 source translations are retained for this English entry.

  • Bulgarian: непроницаем (nepronicaem) — not penetrable
  • Bulgarian: непроходим (neprohodim) — not penetrable
  • Catalan: impenetrable — not penetrable
  • Chinese Mandarin: 不能通过的 — not penetrable
  • Chinese Mandarin: 不能渗透的 — not penetrable
  • Czech: neproniknutelný — not penetrable
  • Czech: nedobytný — not penetrable
  • Dutch: ondoordringbaar — not penetrable
  • Dutch: onpeilbaar — not penetrable
  • Finnish: läpitunkematon — not penetrable
  • French: impénétrable — not penetrable
  • German: undurchlässig — not penetrable
  • Greek: αδιαπέραστος (adiapérastos) — not penetrable
  • Hindi: अभेद्य (abhedya) — not penetrable
  • Latin: impenetrābilis — not penetrable
  • Latin: invius — not penetrable
  • Norwegian Bokmål: ugjennomtrengelig — not penetrable
  • Norwegian Nynorsk: ugjennomtrengeleg — not penetrable
  • Norwegian Nynorsk: ugjennomtrengjeleg — not penetrable
  • Portuguese: impenetrável — not penetrable
  • Romanian: impenetrabil — not penetrable
  • Romanian: de nepătruns — not penetrable
  • Romanian: de nestrăpuns — not penetrable
  • Russian: непроница́емый (nepronicájemyj) — not penetrable
  • Russian: непроходи́мый (neproxodímyj) — not penetrable
  • Spanish: impenetrable — not penetrable
  • Ukrainian: непроникни́й (nepronyknýj) — not penetrable
  • Ukrainian: непробивни́й (neprobyvnýj) — not penetrable
  • Bulgarian: неразбираем (nerazbiraem) — incomprehensible; inscrutable
  • Catalan: impenetrable — incomprehensible; inscrutable
  • Chinese Mandarin: 难以理解的 — incomprehensible; inscrutable
  • Chinese Mandarin: 费解的 — incomprehensible; inscrutable
  • Czech: nesrozumitelný — incomprehensible; inscrutable
  • Dutch: onbegrijpelijk — incomprehensible; inscrutable