Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
impregnably is an adverb meaning "in an impregnable manner". It carries one recorded sense.
in an impregnable manner
“the sight of that bland, impregnably righteous face has been enough to make their blood run cold”
Definitions, synonyms and semantic relations for impregnably come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.