# impregnable

/ˌɪmˈpɹɛɡnəbəɫ/ (US) · /ɪmpɹˈɛɡnəbəl/ (UK) · CEFR C1 · Adjective

Source: https://englishreference.com/word/impregnable
Updated: 2026-10-16

## Definition

so strong that no one can break in, capture it, or defeat it. You use it for castles, walls, or teams that seem impossible to beat.

For teachers: incapable of being captured or broken into by force; completely secure against attack. Extended figuratively to positions, systems, or reputations that cannot be challenged or overcome.

## Examples

- The old castle looks impregnable behind its high walls.
- The home team built an impregnable defence that no opponent could break through all season.
- Perched on sheer cliffs, the fortress remained impregnable for three centuries, its reputation alone deterring armies that might otherwise have tested its walls.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.