Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
impugnable is an adjective meaning "subject to being discredited". It carries one recorded sense.
subject to being discredited
Definitions, synonyms and semantic relations for impugnable come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.